For me, that’s a derived value. An Olympic pool is 50m long, about half that wide (ten lanes; 8 for the swimmers plus one each near each edge for fairness (the waves would be very bad for swimmers swimming alongside the edge)) and about 2m deep.

Reading https://en.wikipedia.org/wiki/Olympic-size_swimming_pool#Spe..., it’s slightly over 50m long (to allow for the mounting of touch panels), exactly 25m wide and at least 2m deep, so 2500m³ is a lower limit, and there is no theoretical upper limit.