There was flooding in some areas along the coast as the dangerous waves reached the harbor.
Randy Chase said he was visiting the area when he saw the waves rush onto the beach, pushing around large logs.
"It was 3 bigger waves that pushed the high tide line up maybe 30 or 50 feet on this beach," said Chase.
An underwater Tongan volcano erupted in the Pacific, triggering tsunami advisories at beaches and marinas across the West Coast.
"Typically when we have tsunami events they're generated by earthquakes, but this, however, was generated by a volcano and volcanic eruptions aren't necessarily exactly the same as earthquake energy," said Brooke Bingaman with the National Weather Service.
Bingaman said this type of event can cause dangerous surf, and people should stay out of the water.
"The dangerous thing is when these fluctuations happen so quickly that means energy is rushing in, and then it's rushing back out. So those currents are very strong, and the undertow can quickly sweep people away," said Bingaman.
Plenty of surfers still went for the big waves at Twin Lakes State Beach in Santa Cruz.
Brothers Terrence and Robert Cubbon said they noticed some powerful currents. "We were just getting pitted out there," said Terrence. "The rip was a little brutal. It sucked me out a few times, I had to climb out."
Robert added, "We definitely were getting sucked out toward the harbor a little more."
The tsunami advisory prompted the Santa Cruz Beach Boardwalk to close for the day. Beaches and marinas up and down the coast were evacuated.
In San Mateo County, two fishermen had to be rescued. They were swept away by a large wave at San Gregorio State Beach.
"Those undertows can be extremely strong, "said Bingaman. "So we want people to realize that just because you don't see a huge tsunami wave coming at you, it doesn't mean that the risks aren't still there."