The Transparent Canoe -- probably not the best choice for the Hudson River.

This seems like a great idea for pristine waters, which the Hudson isn't. (But it's getting better and better.) The Transparent Canoe is an interesting water craft for seeing the bottom or the fish life of crystal clear waters. A  downside is the price, $1900, plus $100 for shipping. It's available at Hammacher.com. Here's their web description:

This canoe-kayak hybrid has a transparent polymer hull that offers paddlers an underwater vista unavailable in conventional boats. Seating two people, the sturdy hull is made of the same durable material found in the cockpit canopies of supersonic fighter jets. The vessel supports up to 425 lbs., displaces a greater amount of water for more surface stability, and paddlers sit lower to the deck, resulting in better balance. Adjustable seats allow paddlers to personalize their leg room. With a lightweight anodized aluminum frame, it can be easily stored or transported. Includes one back seat, one front seat, two fixed estuary paddles, a water bailer, two paddle leashes, and two flotation devices. 33 1/2" W x 133" L x 11" D. (40 lbs.)

http://www.hammacher.com/Product/Default.aspx?sku=78952&refsku=10343