I am actually more apprehensive in lakes that in the ocean. It's weird, but I have an insane fear of snakes and seem to be looking over my shoulder every time I jump into the lake... the pull out is just never fast enough!
In the ocean, I am much more relaxed, even after seeing more "fins" in the ocean than I have ever seen snakes in the lake.
Those Ocearch guys are nuts. They started out with a boat the same size as our family ocean boat about 10 years ago and have now moved onto a virtual ship with a shark lift hanging off the side that converts into a boat lift to carry a 40' Cabo sportfisher. Pretty cool stuff!