Is there a manufacture of a clear bottom kayak?

a few that I have seen and

Ocean Kayak
also has a clear-bottom Scrambler.

I tested it in San Diego a couple years ago and liked it though I was afraid of scratching the plastic.

I’ve seen a homebuilt one on a local lake – the owner bought a cheap used rec boat and added a clear polycarbonate window in fron of the seat.

Wear goggles, learn to roll.

Did that over a wreck
in Lake Superior. Didn’t want to get out of my kayak, but had a dive mask. Fun!

Ocean Kayak Peekaboo
Don’t worry about scratching the window. It’s high end polycarbonate material that is hard to scratch, and minor abrashions don’t affect viewing.