Olly and Beth are best friends and submarines in training, stationed at the Special Underwater Research Facility, or S.U.R.F. The young submarines explore the spectacular underwater world under the guidance of Diver Doug. Some of the characters that join Olly and Beth on their journeys are Skid, Doug's sleek transport vehicle, cantankerous hermit crab Brandt and underwater maintenance assistant UMA. Whether doing a research assignment for Diver Doug or playing with his friends, there's never a dull moment in Olly's world.