A massive North Shore swell that generated waves of 25 to 40 feet kept Honolulu Ocean Safety lifeguards busy today, with large surf expected to continue through the weekend.

As of 5:30 p.m. today, lifeguards had rescued 15 people and conducted an estimated 10,000 “preventative actions” to keep others out of danger, according to Honolulu Ocean Safety spokesperson Shayne Enright.

Just before 2:30 p.m., lifeguards and Honolulu Emergency Medical Services personnel co-responded to three injured men who were out on the rocks in between Ke Iki Beach and Sharks Cove when a large set overtook them. “The men were barely able to get to shore on their own,” Enright said in a news release.

EMS treated them for multiple abrasions from head to toe, but they declined transport to an emergency room.

“Honolulu Ocean Safety strongly advises people to stay off the rocks during high surf. The tide pools are not safe from the powerful waves and you are risking your life,” Enright said.

The National Weather Service extended its high-surf warning for “an extra-large northwest swell” through 6 p.m. Saturday and also expanded the notice to include west-facing shores of Hawaii island. Forecasters advised of the potential for periodic overtopping of vulnerable coastal roadways and wave runup to coastal properties, especially around high tide early Saturday morning.

Surf is expected to trend downward this weekend, with surf potentially dipping below the advisory levels by the end of the weekend, according to NWS. Wave heights of 20 to 30 feet were forecast for the North Shore Saturday, with surf of 15 to 20-feet on west-facing shores and 3 to 5 feet on east- and south-facing shores.

A small-craft advisory in effect for most coastal waters for seas greater than 10 feet is expected to hold through Saturday.

“Looking ahead into next week, a stretch of elevated north and west shore surf is expected, produced by overlapping northwest pulses ranging from large to potentially extra-large, particularly from Wednesday onward,” NWS said.

Surf along east-facing shores will remain slightly elevated through the weekend and remain small early next week. Forecasters said surf along south-facing shores will see an uptick heading into next week, resulting in small to moderate surf, peaking Monday and Tuesday.