Here is a banana-boat that lets you have fun with friends on the water. The Island Hopper Red Shark water sled is a side-by-side towable tube made of puncture resistant, 1100 denier commercial boat materials. It provides you with a stable ride even in rough water. The Red Shark has a max load capacity of 1200 lbs.
This banana boat works for summer camps, businesses, or anyone interested in spending time on the water with friends. Not cheap though.