A Wanaka man who sunk out of sight last night after falling off a yacht on Lake Wanaka is presumed dead.

The distraught survivor of a fishing tragedy spoke last night of desperately trying to keep his brother-in-law's head above water before losing his grip and watching him drown.

Two people have drowned at popular North Island coastal areas this afternoon and two others are missing.

A woman drowned at the mouth of a West Coast river this morning. It is understood she was whitebaiting at the time.