Workers at Hawaiian Oceans Waikiki expect the elevated water levels will force them to alter their operations Thursday and Friday.
"We will be giving lessons, but as far as the rentals, if it gets too big, we won't be renting to the pure novice because it would be too dangerous," said surf instructor Sparky Barros.
The April king tide was the highest tide ever recorded in Hawaii, according to scientists.
The unusually high water levels expected at the end of this week are from the king tide, a large south swell, and some physical oceanographic factors.
"This is the first of what's likely to be recurring flood events," said Chip Fletcher, associate dean in the School of Ocean and Earth Science and Technology at the University of Hawaii at Manoa. "This is a glimpse of our future."
At the Kainalu apartment complex, construction work on a concrete seawall finally started this week after years of damage from the pounding surf.
Other vulnerable areas include basements and low-lying parking garages near the coastline.
"The nature of the flooding could be in three different forms. One would be water coming up over the beach and flooding into whatever buildings lie mauka of the beach. It could be the water table that lies underground beneath us in the coastal plain actually rising and making temporary wetlands on the ground surface, or it could be salt water coming up through the storm drains onto our streets," Fletcher said.
The Hawaii Lodging and Tourism Association is keeping its members statewide informed about potential impacts.
"Take some common sense recommendations such as if you experience flooding before in low-lying areas, make sure you consider sandbagging and are removing materials or possessions from your ground floor," said association CEO Mufi Hannemann.
Fletcher said swimmers and boaters should watch out for unusual water levels and currents.
King tides are also expected around June 23 and July 21 in Hawaii.
Researchers are asking residents to take photos to document high water levels and related impacts and share them here.