As others have said, there isn't much of a view through the bottom of a transparent kayak.

While I was still making up my mind whether I would skin my SOF with polyester or nylon, I had a temporary (for about a year) clear PVC skin. As it was only one tenth of a millimetre thick, it was quite transparent. Even with such a clear skin, there was little to see because my legs blocked most of the view and after a very short time, condensation on the inside of the skin clouded my view.

The condensation seems to be inevitable because the water outside cools the skin and the sun shining through the clear skin warms the moist air inside the kayak.

My personal experience suggests that a transparent kayak is a complete failure as an underwater viewing platform.