Authorities responded to Haleiwa Boat Harbor Sunday afternoon after a catamaran was hit by a large wave, ejecting people into the water.
Ocean Safety officials saw the 40-foot catamaran, Ho’o Nanea, get hit by 15 to 18 foot waves just before 11 a.m.
Lifeguards rescued the people onboard and brought them to shore. Several people were ejected from the boat into the water, officials said.
A 50-year-old woman was transported to the hospital in stable condition.
Paramedics treated five other patients but they refused transportation.
The North Shore is under a high surf warning with surf until 6 a.m. Monday.