Turtles in a marine tank, not a good idea. Hawksbill and others all get very large. They have two Hawksbill's in the Aquarium at Epcot center in Orlando that are in the 4 ft range and who knows what they weigh. And yes they are awsome. As others said, most are also endangered and considered to be a delicacy in far to many parts of the world.
Bonermeister, as for the LFS I would be curious, I thought most marine turtles only left the water to lay eggs. But if he does have one, he should really consider calling the closest aquarium so that it gets the care it needs.
-Scott