Warm ocean currents raise the temperature in cold areas while the cold currents decrease the temperature in warm ocean areas.The Labrador current which is a cold current, lowers the temperature near the north-east coast of North America.
Plunge pool or waterfall lake is a deep depression in the stream bed at the base of the waterfall. It is created by the erosional force of the cascading water. They occur at the youthful stage of the river development.