In the waters off Long Beach, N.Y., swimmers aren't the only ones enjoying the surf: Jellyfish are showing up in droves.

"We were here a few weeks ago and there were a lot of jellyfish. We didn't even go in the water. It was horrible," one teen told CBS News correspondent Susan Koeppen.

And with thousands being stung by jellyfish this summer, lifeguards at Long Beach are armed with spray bottles filled with alcohol and water to take away the pain, says Koeppen.

"We didn't get these a lot years ago," says Chief Lifeguard Paul Gillespie, "but now they're, we're getting, the frequency of them a lot more. ... We've had some of them that were just (so) tremendous that we have to come and pick off the beach."

It's not just beaches seeing a problem, Koeppen points out. "During the recent New York City triathlon, thousands of competitors were stung by jellyfish in the Hudson River.

Experts say the jellyfish explosion is of global concern.

Tourism is hurting in the Mediterranean, where jellyfish seem to have taken over the waters.

"I think the level of jellyfish that we are seeing, and the fact that they outnumber the fish that we want to eat, is unprecedented," observes Margo Stiles, a marine scientist for Oceana, an organization dedicated to, as its Web site puts it, "protecting the world's oceans."

Marine biologists blame the overabundance of jellyfish on several factors, including global warming, the over-fishing of their predators, such as tuna, and pollution -- such as runoff from lawn fertilizer.

Scientists say the number of jellyfish will probably dwindle come fall but, for now, they're putting a sting in some summer fun. And the scientists predict a return of jellyfish next summer, perhaps even more of them.