HONOLULU (KHON2) — Hundreds of people are expected to hit the water Monday, Sept. 2, but it won’t be an easy swim.

They’re participating in the Waikiki Roughwater Swim Competition.

It’s supposed to be one of the most difficult swim races in Hawaii. So tough — that it was the original swim leg for the Ironman.

Back in 2016, 300 people had to be rescued because they kept getting dragged backward.

The event runs from 8:30 a.m. to 11 a.m.

If you still want to sign up, you can at the event, but it’ll cost you $120.