Officials said the man was on a boat at Silverwood Lake, just west of Big Bear, when he jumped into the water and then was in distress. His friends jumped in to help him but were unsuccessful.
An officials with the sheriff's department said they got a call a little after 4 p.m. to help state authorities.
The dive team was not able to find the man and stopped the search when the sun went down. They said they would continue the search at sunrise Monday.