>>12925809Napkin math to support this.
Wailord is 14.5m long. Let's say based off his official art that he could roughly be modelled as a cylinder of that length and a diameter of about half that, so 7.25m, giving a radius of 3.125m.
That gives him a volume of pi * radius squared * length, so 444.6 metres cubed.
He also weighs 398kg, meaning an average density of around 0.9kg per metre cubed.
Water has a density of one THOUSAND kg/m^3, Wailord is literally more than a thousand times less dense than an equal volume of water, and still a few dozen percent less dense than Oxygen.
Did some similar calculations based on Steelix, he has a density somewhere around 24kg/m^3, while actual steel is closer to 8,000kg/m^3.