In order to protect the ocean, participants will plunge into it Saturday during the Surfrider Foundation's fourth annual Clean Ocean Paddle-A-Thon.
Entrants will accept pledges and then propel their kayaks, paddleboards, surfboards, bodyboards or other human-powered craft from the Balboa Pier on courses ranging from one-half to 3 1/2 miles.
Swimming is also allowed. No entry fee is charged.
The participants who raise the most money will win prizes, and anyone who turns in at least $50 on the day of the race will receive a T-shirt.
Registration begins at 8 a.m., and the event starts an hour later.
A smooth-water paddle for kayakers on the harbor side of the peninsula also will begin at 9 a.m.
Proceeds from the event will go toward Surfrider programs including Teach and Test, which provides high school science classes with material to test ocean and river water for bacteria; Kids Art for the Environment, which brings inner-city students to the Orange County Marine Institute and the Bowers Museum to learn about the ocean and create environmental-themed art; and Blue Water Task Force, which responds to incidents of pollution and investigates how to prevent it.
Information: (714) 631-6273.