It is not if all you know are football fields and not American football fields.

I still don’t know how they even compare.

That's why we use the %fill of an Olympic Sized Pool - doesn't matter from what continent the field comes, they fill the pool equally.

Aren't there significant differences in allowed depth (from minimum of 2m to maximum of 3m)?

Good catch. We've run into a problem somewhere along this journey of comparing the compression strength of a snails tooth to the tensile strength of a spiders web.

So a snail's tooth can only hold a 2m deep worth of Olympic pool (sea)water, but it breaks before you get to a 3m deep pool.

Only if you don’t understand that 3300 one pound bags of sugar is 3300 pounds. What an enlightening conversation here. Crème de la crème of modern thinkers.