Learn about buoyancy with the Ocean Cleaning Seahorse. Recycle a plastic water bottle for this fun activity. Fill the bottle with water and then drop in the seahorse. Squeeze the bottle to increase the pressure and watch your seahorse dive to hook the deep sea trash. Release the bottle and the seahorse floats back to the top. This DIY set includes a Learning Booklet teach all about pressure and density while your child is just having fun. You can dive over and over again! No tools, glue or batteries required. Reuse your plastic water bottle.