This is how a horseshoe crab swims...

It’s rare to see a horseshoe crab (face hugger) swimming because they hardly ever do. When they do swim, they swim upside down. The horseshoe crab has been around for 200 million years before the dinosaurs. They have 10 eyes, 10 claws, 7 pairs of legs, and blue blood. They are basically harmless and their claws are not strong enough to hurt a person. Their blood is highly valued in the medical industry and is worth $15,000 per quart. Fortunately, they are not endangered, or even listed as threatened. They shed their exoskeleton regularly as they grow. Details about the clear kayak can be found here