大象传媒

The teams test their knowledge of buoyancy in Hide and Sink, where they are asked to conceal various items which Richard has borrowed from Ninja Nan's Nannexe in the gunge tank. They have to work out which items they think will sink when dropped into the tank.

Meanwhile, Richard challenges the Lab Rats to walk on water in a race to run across the surface of the lake at his top-secret testing ground. Two crazy crafts are used for this test - a giant human hamster ball filled with air, and a bizarre hydrofoil water bike which moves when the rider pushes the front wing of the craft into the water in a pump-like motion. But is it even possible to walk on water, let alone run?