The most common above-ground pool shapes are square, oval, and circular swimming pools. Their simple shapes makes above-ground swimming pools smaller and shallower on average than most in-ground pools, and thus are easier to maintain. The most common above-ground pool shapes are square, oval, and circular swimming pools. Their simple shapes makes above-ground swimming pools smaller and shallower on average than most in-ground pools, and thus are easier to maintain. The most common above-ground pool shapes are square, oval, and circular swimming pools. Their simple shapes makes above-ground swimming pools smaller and shallower on average than most in-ground pools, and thus are easier to maintain. The most common above-ground pool shapes are square, oval, and circular swimming pools. Their simple shapes makes above-ground swimming pools smaller and shallower on average than most in-ground pools, and thus are easier to maintain.