When above-ground swimming pools became popular in the 1950s-1960s, the most popular and common shape available was the classic round. It still remains popular, but has been updated with decking, fencing, stairs and a safety gate. Doughboy, the manufacturer of this pool, recently started making in-ground swimming pools in addition to above-grounds. Technically, Doughboy in-grounds are actually above-ground pools that can be sunk into the ground up to a depth of 7 feet.
It's all part of what the company calls its "Doughboy Buried Pool Program."