Has anyone managed to find anything on suction dredging at...

Has anyone managed to find anything on suction dredging at depths of 300m? All I've found is material that indicates it is only possible at a little over 100m depth.

e.g.

http://www.vanoord.com/webfront/base.asp?pageid=192#


I see BON asserts that "current marine mining and dredging technologies can cope with depths of 600m". However, I don't see how it could be by suction dredging.

Animated Film clip here of a suction dredger at work.

http://www.vanoord.com/webfront/swf/vanoord_player.asp?vom=http://www.vanoord.com/public/Downloads/Movies/3D_animaties/Volvox%20Olympia_flv_512kbit.flv