A powerful magnitude-8.3 earthquake off the coast of Chile was forecast to send a small tsunami to the Hawaiian Islands early Thursday morning, where experts deemed an evacuation unnecessary but nonetheless directed local swimmers and boaters to stay out of the water during early morning hours.

Forecasters expected the tsunami to reach Hawaii shortly after 3 a.m. with maximum wave heights of just over 3 feet. They expected its effects to dissipate by 7 a.m. People should stay out of the water and off the beaches during that period, they advised.

“The shoreline is going to be dangerous,” Gerard Fryer, a senior geophysicist with the Pacific Tsunami Warning Center, said Wednesday during a news briefing at the center’s new headquarters on Ford Island.

Because of the tsunami advisory, Hanauma Bay and coastal areas around the state will close Thursday morning.

The state Department of Land and Natural Resources said it would close coastal and low-lying state parks and forest areas, including wildlife sanctuaries, natural area reserves and game management areas, on all islands. DLNR said small boat harbors would remain open for boat owners who want to take their vessels out in anticipation of turbulence.

The public was advised to avoid coastal waters, beaches and rocky shorelines.

Maui County said it would close all beach parks as ocean conditions are assessed, and the Kipahulu campground at Haleakala National Park on Maui was also closed.

A planned, free workshop on disaster preparedness scheduled for Wednesday at 6:30 p.m. in Waianae was canceled and will be rescheduled for next month, the Honolulu Department of Emergency Management said.

Only Wailoa Boat Harbor in Hilo might see flooding from Thursday’s tsunami, and if so it wouldn’t be much, Fryer said.

At the boat harbor Wednesday, Alvin Maeda was part of a steady flow of boat owners who hauled trailers into the parking lot to load their fishing or pleasure vessels to get them to higher ground. Maeda, 65, rounded up several friends to help him haul his 36-foot fishing boat, Sweet Sherri, to a friendʻs property about a mile away. The job was done well before dark Wednesday.

Maeda, a retired ironworker foreman, then returned to the harbor to talk with friends and watch the pouring rain and the flurry of activity at the harbor, which is in the tsunami inundation zone. Maeda said, “It’s better than taking chances, yeah?”

The canoe halau at Hilo Bayfront was still packed with vessels at dusk, and a canoe practice was wrapping up as if it was a normal, rainy day, but the Kamehameha Canoe Club was busy preparing for the possible threat. The club had summoned about 50 members to move a half-dozen practice canoes away from the water to a grassy area on higher ground.

On Oahu, the tsunami effect was expected to hit Barbers Point first and then fan out in both the leeward and windward directions, according to the tsunami warning center.

“It would look like a rapidly rising tide, rather than a wave,” Fryer said.

Kevin Allan, acting city Ocean Safety chief, said that water coming in from even the smallest tsunami waves could have a significant impact in shallow waters.

“All that water coming in towards the land has to go back out, so it really does cause a strong current,” Allan said.

Even after the early morning hours, Allan said, “keep an eye on the water, look at it before you go out,” and consult with lifeguards first.

No evacuations were planned and no sirens were expected to be sounded, Honolulu Mayor Kirk Caldwell said.

Bus service is expected to run on a regular weekday schedule.

George Szigeti, president and chief executive of the Hawaii Tourism Authority, said hotel and resort officials statewide have been urged to pass on the precautions to the state’s visitors.

An Oahu Civil Defense hotline has been set up for tsunami-related questions or concerns. It is 768-2489.

A skeleton crew was expected to remain at the Emergency Operations Center through the night to monitor the incoming waves, said Peter Hirai, Department of Emergency Services deputy director.

The Chilean quake was followed by at least 17 aftershocks, the strongest at magnitude-7.0.

Off Kailua Beach, residents and business workers were taking the initial tsunami watch, which preceded the less serious advisory, in stride.

“There’s not really anything we can do,” said Kaleo Schneider, manager at Buzz’s Original Steakhouse, which is within sight of the shore. “If the sirens go off, we’re out of here. That’s all we can do if there’s a warning. All we can do is lock up and leave.”

Peter Francke, a 59-year-old Kailua resident, said, “We’ve been through a bunch of these and it never happened.”

Star-Advertiser reporters Leila Fujimori and Kevin Dayton contributed to this report.