No sign has been found of a missing 24-year-old swimmer after five days of searching since he disappeared while swimming in Wailuku River, Big Island firefighters said yesterday.

Fire personnel will scale down the search for the missing swimmer to periodic helicopter searches until additional information becomes available, a fire department news release said.

Ryan J. Ritzel, 24, vanished Tuesday afternoon while swimming with five co-workers in an area called Boiling Pots, police said. Ritzel is a cruise ship employee from Soquel, Calif.

Firefighters made numerous passes along the river and conducted a ground search the first day. Divers did not enter the water because of strong currents from heavy rain and rocks.

A fire helicopter searched yesterday from Boiling Pots to Hilo Bay breakwater, and ground teams searched the river banks. Divers entered the river where they could.