Portable Ejector, Surface Sluice

These used to be the only option when it came to the underwater sluice, however the fixed ejector, surface sluice type has taken its place in that sense. Even though they cannot be found as easily as they could in the past, they have lasted and served as accessory suction nozzles for this kind of dredge, mainly in the three and four inch sizes that work fine in shallow waters.

Portable Ejector, Underwater Sluice
These are quite old and used to be used for dredging the past. There are some people still use them for moving big amounts of overburden or for deep water diving operations.  

Sub Surface or Submersible Dredge
These dredges are a real combination type and they are usually made to work for underwater operations only. The suction tube and sluice is suspended from a float that also carries the centrifugal pump. This is convenient in deep operations due to the fact that the material needs to be carried only half way up. It is simpler to work over long periods of time because only the suction hose needs to be handled and not the whole sluice box.