Run like a kid again!
To measure it I usually count paces. That is accurate enough to determine if it is 25 yards or meters however sometimes pools are odd lengths like 18 or 20 yards. In that case you might want to try counting tiles on the floor and then measure 1 tile and multiply to calculate the length.
Son, when you participate in sporting events, it's not whether you win or lose; it's how drunk you get. -- Homer Simpson