Depends on where you dive, there can be plenty to see if do proper research and know what to look for. It is also quite a bit more of a challenge. Rivers and canals used to be our main source of moving commodities so many old relics from the past can be found. In other cases some pretty impressive fossils like the megladon teeth in my profile picture. I have had some good fortune in eastern rivers as well as the Sante Fe and Suwannee rivers.