That water off Long Island's shores? It really is turquoise-colored.

If you’ve visited a Long Island beach this summer, you may have noticed an unusual phenomenon: the water appears turquoise-like, and looking a lot like the Caribbean Sea.

That's because of phytoplankton-like algal blooms that occur during early summer. The blooms happen as a result of upwelling, an oceanographic process that occurs when wind blows parallel to the shore, bringing deeper ocean water to the surface, Newsday meteorologist Geoff Bansen said.

“It takes a lot of the warm water that’s sitting there and pushes it away,” Bansen said. “And so what happens is when you push that warm water off the top … the cold water has no choice but to come up from below.”

The deeper water is nutrient-rich, which stimulates algae blooms and a bluer appearance. In June, the water stimulates a particular algae type, coccolithophores, which is composed of calcium carbonate and detectable via satellite, according to Chris Gobler, a professor at Stony Brook University’s School of Marine and Atmospheric Sciences.

“You can think about them leaving a chalky trail behind them that can be picked up by the satellites,” Gobler said in an interview with NewsdayTV. “This happened two years ago as well, and seems to be happening with increased frequency.”

Joaquim Goes, a professor of remote sensing research and biological oceanography at Lamont Doherty Earth Observatory at Columbia University in Palisades, said coccolithophores turn the water turquoise through a light scattering process. Normal phytoplankton, in contrast, absorbs different light shades, creating a brownish green that can be seen from space.

Goes said he’s surprised this phenomena is present on Long Island this year. A similar bloom occurred last year.

“It’s appearance off the coast of New York is pretty strange, because typically, this is not the kind of waters you expect them in,” he said.

Gobler said if you’re noticing algal blooms and turquoise water, it’s a sign water is not as clear as it should be. He said, in general, water should be clear and clean.

“Long Island’s ocean waters are generally very clean and very clear and,I’ll add, very safe,” Gobler said.

At Robert Moses State Park Wednesday afternoon, beachgoers were largely unaware of the water appearing more turquoise.

Joyce Hill, of Amity Harbor, said while she didn’t notice the phenomenon, the water near McCallister Beach was clear when fishing.

As the summer progresses, the turquoise-like water along Long Island's shores will dissipate: The phenomenon fades as water gets warmer.

“When the wind pattern shifts in direction and the extent to which it’s sustained, there’s probably less of that upwelling,” Gobler said. “And as the water warms the levels of nutrients will tend to go down also, so essentially it runs out of fuel.”