Oceans Engineering Ltd.
All Oceans - Mechanical Handling Underwater
http://www.alloceans.co.uk/

Underwater Resources, Inc.
Official website for Underwater Resources, Inc.
http://underwater-resources.com/

Novaray Underwater ROV
Underwater ROV (Remotely Operated Vehicle) Operates in high currents - maritime search and rescue, maritime port and ship security, underwater treasure salvage. All in one underwater rov
http://www.novaray.com

Lubell Labs Inc.
Lubell Labs offers underwater speakers, underwater loudspeakers, underwater acoustic transducers, diver recall systems, synchronized swimming sound systems, amplifiers, analog and digital recorders, wired and wireless microphones, sound reproduction equipment, and complete air and underwater sound systems.
http://www.lubell.com/

Society for Underwater Technology
a multi-disciplinary learned Society which brings together individuals and organisations from more than 30 countries who have a common interest in underwater technology, ocean science and offshore engineering.
http://www.sut.org.uk/

The Society for Underwater Technology, Houston
A multi-disciplinary learned Society bringing together individuals and organizations from more than forty countries who have a common interest in underwater technology, ocean science, and offshore engineering.
http://www.suthouston.com/

Simon Fraser University
Underwater Research Laboratory (URL). Specializes in underwater studies in the areas of acoustics, sonar, autonomous underwater vehicles, column surveys, signal processing and target detection. Page lists projects and personnel.
http://www.ensc.sfu.ca/research/url/

Benthic Telesis, Inc.
Provides mechanical design engineering, finite element analysis, systems engineering and small batch manufacturing. Specializing in the underwater and marine environments.
http://www.benthic-telesis.com

Sub Sea Sonics
Underwater acoustic release, underwater timed release, manufactured by Sub Sea Sonics for the marine industry.
http://www.subseasonics.com/

Carrillo Underwater Systems
Manufactures underwater lights, cameras, and diver "squak boxes". Specializes in low voltage underwater video, helmets, and navigation lights for commercial and recreational divers.
http://www.carrillounderwater.com/