When you step into a very full bath or hot tub sometimes the water overflows. But when you step into a lake and swim you don't notice the level of the water rise at all. Explain why this is.?

Archimedes principle states that the volume water displaced is equal to your weight; for a small total volume of water it will overflow; but in a lake where the total volume is huge the volume displaced by your weight is spread out over such a large volume you cannot notice the change