Company lists · Data refreshed September 2026

Top 25 Marine and subsea consulting firms based in the United States

Name: Marine and subsea consulting firms based in the United States
Creator: RevenueBase
License: https://creativecommons.org/licenses/by/4.0/

Compiled by the RevenueBase Data Team Data refreshed Sep 28, 2026 2,325 companies tracked

RevenueBase identified 2,325 marine and subsea consulting firms headquartered in the United States as of September 2026 and tracks 123,646 professional contacts across them, including 49,214 with verified work emails. Houston is the largest hub.

This list covers marine and subsea consulting firms headquartered in the United States, matched on what each company actually does as described in its own words. Ranked by team size, largest first. Every row shows the company's own description, its RevenueBase Smart Search rating, and when it was last checked. Data refreshed September 28, 2026.

Published by RevenueBase, a B2B data infrastructure company. This list was built with RevenueBase Smart Search, the natural-language company search RevenueBase customers use to build their own targeted lists and unlock verified emails and direct dials at the companies on them. How these lists are built and judged.

How to read this list HQ checked on every row RevenueBase Smart Search rating on every row Refreshed Sep 28, 2026 86% judged on-target in blind review

2,325Companies

123,646Contacts tracked

49,214Verified emails

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The 25 largest marine and subsea consulting firms based in the United States

Ranked by team size

Top 25 of 2,325 marine and subsea consulting firms based in the United States, ranked by team size, largest first. Data refreshed Sep 28, 2026. RevenueBase Smart Search rates how each company's information relates to marine and subsea consulting firms: strong evidence (its own description names it), partial (names part of it), indirect (matched on the rest of its profile rather than the description shown). Click a contact count to view that company's people.
#	Company	RevenueBase Smart Search	Headquarters	Employees	Contacts
1	Tetra Tech	Indirect evidence	Pasadena, CA, United StatesHQ checked Sep 28, 2026	10001+	12,999 contacts →
	Indirect evidence “Tetra Tech is the leader in water, environment and sustainable infrastructure, providing high-end technical and engineering services for projects worldwide.” Source: RevenueBase Database · checked Sep 28, 2026
2	Oceaneering	Indirect evidence	Houston, TX, United StatesHQ checked Sep 28, 2026	10001+	12,031 contacts →
	Indirect evidence “Oceaneering is a global technology company delivering engineered services and products and robotic solutions to the offshore energy, defense, aerospace, and manufacturing…” Source: RevenueBase Database · checked Sep 28, 2026
3	Terracon	Partial evidence	Olathe, KS, United StatesHQ checked Sep 28, 2026	5,001-10,000	6,113 contacts →
	Partial evidence “Terracon is a 100 percent employee-owned consulting engineering firm providing quality services to clients.” Source: RevenueBase Database · checked Sep 28, 2026
4	Brown And Caldwell	Indirect evidence	Walnut Creek, CA, United StatesHQ checked Sep 28, 2026	1,001-5,000	2,473 contacts →
	Indirect evidence “Headquartered in Walnut Creek, Calif, Brown and Caldwell is an employee-owned firm with 2,100+ professionals serving clients locally and globally from 52 locations.” Source: RevenueBase Database · checked Sep 28, 2026
5	Geosyntec Consultants	Partial evidence	Boca Raton, FL, United StatesHQ checked Sep 28, 2026	1,001-5,000	2,393 contacts →
	Partial evidence “Geosyntec is a consulting and engineering firm that works with private and public sector clients to address new ventures and complex problems involving our environment, natural…” Source: RevenueBase Database · checked Sep 28, 2026
6	Providence	Partial evidence	Baton Rouge, LA, United StatesHQ checked Sep 28, 2026	n/a	2,232 contacts →
	Partial evidence “Providence is an employee-owned engineering and environmental consulting firm.” Source: RevenueBase Database · checked Sep 28, 2026
7	ECS Group Of Companies	Partial evidence	Chantilly, VA, United StatesHQ checked Sep 28, 2026	1,001-5,000	2,210 contacts →
	Partial evidence “ECS Group of Companies is a Chantilly, VA-based consulting engineering firm.” Source: RevenueBase Database · checked Sep 28, 2026
8	Olsson	Indirect evidence	Lincoln, NE, United StatesHQ checked Sep 28, 2026	1,001-5,000	2,108 contacts →
	Indirect evidence “Olsson is an engineering firm made up of people who craft expert solutions and designs that improve communities.” Source: RevenueBase Database · checked Sep 28, 2026
9	Helix Energy Solutions Group	Indirect evidence	Houston, TX, United StatesHQ checked Sep 28, 2026	1,001-5,000	1,706 contacts →
	Indirect evidence “Helix Energy Solutions, headquartered in Houston, Texas, is an international offshore energy services company that provides specialty services to the offshore energy industry…” Source: RevenueBase Database · checked Sep 28, 2026
10	GEI Consultants, INC	Indirect evidence	Woburn, MA, United StatesHQ checked Sep 28, 2026	1,001-5,000	1,604 contacts →
	Indirect evidence Source: RevenueBase Database · checked Sep 28, 2026
11	UES	Indirect evidence	Orlando, FL, United StatesHQ checked Sep 28, 2026	1,001-5,000	1,595 contacts →
	Indirect evidence “UES provides professional engineering, environmental, testing and inspection services to clients across the United States.” Source: RevenueBase Database · checked Sep 28, 2026
12	Exponent	Partial evidence	Menlo Park, CA, United StatesHQ checked Sep 28, 2026	1,001-5,000	1,560 contacts →
	Partial evidence “In an era of accelerating change, Exponent is the only premium engineering and scientific consulting firm with the depth and breadth of expertise to solve our clients’ most…” Source: RevenueBase Database · checked Sep 28, 2026
13	Weston Solutions, INC	Indirect evidence	West Chester, PA, United StatesHQ checked Sep 28, 2026	1,001-5,000	1,441 contacts →
	Indirect evidence “Weston Solutions, Inc.(Weston) is a 100% employee-owned environmental and infrastructure services firm committed to safety and providing measurable client value.” Source: RevenueBase Database · checked Sep 28, 2026
14	Partner Engineering & Science, INC	Indirect evidence	Torrance, CA, United StatesHQ checked Sep 28, 2026	1,001-5,000	1,358 contacts →
	Indirect evidence “Partner Assessment Corp.” Source: RevenueBase Database · checked Sep 28, 2026
15	Knight Piesold	Partial evidence	Denver, CO, United StatesHQ checked Sep 28, 2026	1,001-5,000	1,231 contacts →
	Partial evidence “Knight Piésold is an employee-owned, global consulting firm providing specialist services to the mining, power, water resources, and infrastructure industries.” Source: RevenueBase Database · checked Sep 28, 2026
16	Moffatt & Nichol	Indirect evidence	Long Beach, CA, United StatesHQ checked Sep 28, 2026	1,001-5,000	1,178 contacts →
	Indirect evidence “Moffatt & Nichol is a leading U.S-based global infrastructure advisor specializing in the planning and design of facilities that shape and serve our coastlines, harbors and…” Source: RevenueBase Database · checked Sep 28, 2026
17	Apex Companies	Indirect evidence	Rockville, MD, United StatesHQ checked Sep 28, 2026	1,001-5,000	1,137 contacts →
	Indirect evidence “Who is Apex?” Source: RevenueBase Database · checked Sep 28, 2026
18	Haley & Aldrich	Indirect evidence	Burlington, MA, United StatesHQ checked Sep 28, 2026	501-1,000	1,124 contacts →
	Indirect evidence “Haley & Aldrich is committed to solving our clients’ most meaningful challenges in the built and natural environments.” Source: RevenueBase Database · checked Sep 28, 2026
19	Barr Engineering CO	Partial evidence	Minneapolis, MN, United StatesHQ checked Sep 28, 2026	1,001-5,000	1,088 contacts →
	Partial evidence “Barr provides engineering and environmental consulting services to clients across the Midwest, throughout the Americas, and around the world.” Source: RevenueBase Database · checked Sep 28, 2026
20	Gulf Companies	Indirect evidence	Houston, TX, United StatesHQ checked Sep 28, 2026	1,001-5,000	1,046 contacts →
	Indirect evidence “At Gulf Companies, we are driven by our mission to serve a vital role in the global energy industry.” Source: RevenueBase Database · checked Sep 28, 2026
21	Trinity Consultants	Indirect evidence	Dallas, TX, United StatesHQ checked Sep 28, 2026	1,001-5,000	961 contacts →
	Indirect evidence “Trinity Consultants is a global team of experts helping organizations solve complex challenges in environmental compliance, ecological protection, infrastructure performance, and…” Source: RevenueBase Database · checked Sep 28, 2026
22	GZA Geoenvironmental, INC	Indirect evidence	Norwood, MA, United StatesHQ checked Sep 28, 2026	501-1,000	880 contacts →
	Indirect evidence “Founded in 1964 as a soils and foundations specialty consultant, GZA GeoEnvironmental, Inc.(GZA) has grown into a full-service company providing its clients with highly…” Source: RevenueBase Database · checked Sep 28, 2026
23	ABS Consulting	Partial evidence	Spring, TX, United StatesHQ checked Sep 28, 2026	1,001-5,000	875 contacts →
	Partial evidence “ABSG Consulting Inc.(ABS Consulting) is part of ABS Group of Companies, a global leader in safety and risk management for critical infrastructure worldwide and a wholly owned…” Source: RevenueBase Database · checked Sep 28, 2026
24	ATC Group Services LLC	Indirect evidence	Lafayette, LA, United StatesHQ checked Sep 28, 2026	1,001-5,000	865 contacts →
	Indirect evidence “ATC Group Services LLC is now Atlas.” Source: RevenueBase Database · checked Sep 28, 2026
25	Weeks Marine, INC	Partial evidence	Cranford, NJ, United StatesHQ checked Sep 28, 2026	1,001-5,000	847 contacts →
	Partial evidence “Founded in 1919, Weeks Marine, Inc.” Source: RevenueBase Database · checked Sep 28, 2026

RevenueBase Smart Search

RevenueBase Smart Search assesses information from a company’s LinkedIn profile, information supplied directly by the company, its website, and other publicly available sources. It uses that information to rate how closely the company relates to this list’s category: marine and subsea consulting firms. Every row carries its rating and the description the rating was read from, so each one can be checked rather than taken on trust.

Strong evidence: The company's own public description of its business names marine and subsea consulting firms.
Partial evidence: Its own public description names part of marine and subsea consulting firms, so it works in or next to the category without describing itself that way.
Indirect evidence: The description shown does not name marine and subsea consulting firms. The match rests on the rest of the company's public profile rather than the one sentence quoted here, so this is the rating to check first.

RevenueBase Smart Search is how these lists are built: RevenueBase's data engine and AI assemble the companies that match a category defined in a user's own words, so a list can be about what companies actually do rather than about whichever industry code they were filed under.

Showing 25 of 2,325 marine and subsea consulting firms based in the United States

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Marine and subsea consulting firms based in the United States at a glance

As of Sep 28, 2026

39.8%Verified-email coverage

53.2Average contacts per company

11-50Median size (employees)

12.3%Largest-city concentration · Houston

Sep 28, 2026Page data refreshed

Companies by employee count

1-10

1,068

11-50

757

51-200

325

201-500

501-1,000

1,001-5,000

5,001-10,000

10001+

Email recency for this list is measured worldwide rather than for United States, so it is reported there. Company counts and contact totals on this page are exact for United States, over 2,325 companies.

How this list was built

Company categories are rarely black and white. RevenueBase reads each company's own description of its business to decide whether it belongs among marine and subsea consulting firms, so some rows will be adjacent to the category rather than pure plays. The description and RevenueBase Smart Search rating on every row are there so you can check each match yourself.

Source: The RevenueBase company graph: 60 million companies and 398.9 million professional contacts resolved from primary sources, queried with RevenueBase Smart Search, the natural-language company search available to every RevenueBase user.
What qualifies: Companies headquartered in the United States whose own description of what they do matches “marine and subsea consulting firms”. Matching reads each company's description, not its industry code or its name.
RevenueBase Smart Search: RevenueBase Smart Search is how this list is assembled and how each row is rated. RevenueBase's data engine and AI assess a company's LinkedIn profile, information supplied directly by the company, its website and other publicly available information, then relate it to a category defined in a user's own words. Each row is rated strong evidence (its own description names marine and subsea consulting firms), partial evidence (it names part of the category) or indirect evidence (the description shown names none of it and the match rests on the rest of the company's profile). The description supporting each rating is quoted on the row.
What we exclude: Companies whose own description does not clearly place them among marine and subsea consulting firms, and records with no verified work email. Companies headquartered outside United States are excluded even when they keep an office there.
Match quality: In blind human judging of this matching method, 86% of matched companies were on target. Expect roughly 1 in 7 rows to be adjacent to the category rather than a pure play. Every row shows the company's own description and its RevenueBase Smart Search rating so you can judge each match yourself. Read the full methodology: how the lists are built, how the judging worked, and what the figure means.
Ranking: Team size, largest first: companies are ordered by the number of professionals RevenueBase tracks at each one. Employee ranges shown are reported bands, for context.
Verification: Every listed company carries at least one verified work email, 49,214 across the full list. Contacts re-verify on a rolling cadence, and each contact's own verification date is shown inside RevenueBase.
Refresh: This page's figures were pulled from the company graph on September 28, 2026. Lists refresh periodically as the graph is re-checked.
Corrections: Wrong category, wrong headquarters, or a company that has closed? Use “Report an issue” on any row. Reports go to the RevenueBase Data Team and feed back into the company graph.

Marine and subsea consulting firms by metro

Frequently asked

What is RevenueBase Smart Search?

RevenueBase Smart Search is how RevenueBase decides which companies belong on this list and how strongly each one fits. Its data engine and AI assess a company's LinkedIn profile, information supplied directly by the company, its website and other publicly available information, then relate it to the category the list is about. Each row is rated strong evidence when the company's own description names marine and subsea consulting firms, partial evidence when it names part of the category, and indirect evidence when the description shown names none of it and the match rests on the rest of the company's profile.

How many marine and subsea consulting firms are there based in the United States?

RevenueBase identified 2,325 marine and subsea consulting firms headquartered in the United States as of September 2026, matched on each company's own description of what it does rather than its industry code.

What is the largest company on this list?

Tetra Tech, headquartered in Pasadena, tops this list with the largest team on record.

Which city has the most marine and subsea consulting firms?

Houston leads with 286 headquartered companies, followed by Seattle (44) and Miami (37).

How do I get contact information for these companies?

A free RevenueBase account lets you run this exact search and work the top results, verified emails and direct dials included. Upgrading unlocks all 49,214 verified decision-maker contacts tracked across these 2,325 companies.

How current is this list?

The list refreshes periodically as the company graph is re-checked. This page's figures were pulled on September 28, 2026.

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About this data

RevenueBase is a B2B data infrastructure company. Its company graph covers 60 million companies and 398.9 million professional contacts, with emails verified on a rolling cadence rather than scraped once and left to decay. These company lists are generated directly from that graph with RevenueBase Smart Search, the same natural-language company search every RevenueBase user has: describe a market in plain words, get the companies that match, and add verified emails and direct dials for the people at them. It is the same data that powers RevenueBase's B2B data products, and a free account includes 500 credits to start. How these lists are built and judged.