Biological sampling (grab, diving, etc)
Remote sampling (video, etc)
Remote sensing imagery (SSS, Multibeam, etc.)
Modelled products (hydrodynamics, derivatives of imagery, etc)
The above links focus on high-resolution hydro-acoustic and underwater photographic/video seabed mapping and habitat classification techniques and interpretation. Also for the Coastal Remote Sensing toolkit for managers and scientists planning you can use electro-optical remote sensing techniques to map and monitor coastal aquatic environments.
Underwater pictures taken in Parks Victoria- click on image to go to case studies