As the temperatures climb into the 90s and the long, mild spring fades into memory, families are moving into their backyards, where in many Montgomery County communities, swimming pools are so abundant the land appears to be dotted with ponds.

Poolside settings are the scenes of graduation parties, weddings, family meals and relatives. The pool area can become an outdoor living room that keeps the family close to home on hot and humid days.

Whether it's a standard, built-in pool with a deep end and a diving board, a tub-like model with motorized current or a subterranean pool, it serves the same purposes: The pool is the place for cooling off, socializing and exercising.

The Massaros of Silver Spring, for instance, came to Montgomery County from Huntington, Long Island, where the beach was just minutes away. They recreated a bit of Long Island Sound by adding a pool 40 feet long to their back yard, where Gabriel Massaro, a school administrator, swims laps daily. Daughter Gabriele, 17, has invited 125 "close friends" from her senior class at Magruder High for a pool party. Meanwhile, Shep the family dog sits panting on the steps in the shallow end, cooling off after a romp with the dog next door.

Don Finn, their neighbor across the back fensce, like to settle into the spa end of his pool with a martini when he comes home from work. Many home pools in the area have water and air jets that create a whirlpool effect. They're often called "jacuzzis," after a manufacturer of spa pumps, whirlpool baths and pool equipment.

"Washington is the place to have a pool. It's so hot and humid here," said Finn, who grew up in Pittsburgh where, he said, he hitchhiked 10 miles to go swimming.

Finn's nine children, his five nieces and nephews and the family's Yorkshire terrior Smitty are in the water most of the summer.A family wedding took place at the pool last summer, and during the winter, 13-year-old Laurie skated on its surface. But leaving the pool filled was a mistake, her father said, because the water was filled with dirt and leaves when it thawed in spring.

"At first it was a novelty, like having a boat, and we invited lots of people over," said Sylvia Palmer, whose Kenwood home has a 37 1/2-foot pool in the backyard. "One of the main reasons we were pleased that the house had a pool is that we wanted to keep the kids at home rather than on the street."

It has some of that effect, but Sam Palmer, 17, said although the home pool is great for cooling off, but he goes to a public pool in Bethesda when he wants to be with his friends.

The pool is less a novelty than a summertime extension of the house. "We don't even mess up the living room. We do everything out there -- eat meals, work, read newspapers and magazines," said Sylvia Palmer.

"I use it a lot," said Chad, 6, who claims to have learned to swim from the neightbors' ducks.

There is no known tally of the number of private pools in Montgomery County although the building permit office reports it issues 20 to 24 swimming pools permits a month from April to September. There are eight public pools in the county, and about 350 private community or apartment pools.

Richard Dixon, sales manager for Anthony Pools, said business has been excellent this year: "We're well ahead of our goals for the year. People can't go anywhere else. They can't move up in life style to a bigger home because of the mortgage rates. So they're adding improvements."

State Del. David Scull had wanted a pool for years, but wife Nancy wanted a porch. They compromised on a pool inside a porch at their Chevy Chase home.

The pool is 7 feet by 14 and is enclosed by the back porch. Two jets of water at one end of the tub-like pool create an artifical current that Schull swims against, enabling him to exercise by swimming in place. "It's like a salmon run," he said.

It took Scull, who is 6 feet 4, eight months to locate the Texas firm that sold the pool he wanted, and his biggest concern was that the current wouldn't be strong enough. But he couldn't find a completed pool like it on the east coast, he said, so he took his chances.

"It's the most usable recreational investment. I have ever done," he said. "You might think it boring but I feel it's more enjoyable than lap swimming. You get a massage while you do it, the sun is streaming in and you can do it all year round."

Point the jets of water up toward the surface and they create a tumble of rapids in which Heather, 5, and her friends love to play. The 3 1/2-foot-deep pool also has a heater and six jets of water that can turn it into a "jacuzzi."

"We don't call it a tub because then people are afraid to get in it. They think they're supposed to go in nude," said Nancy Scull. "We'd advertise a party and say this was part of it, but when we asked if they brought suits they said, no, that they brought suits they said, no, that they had a cold or something. Then we'd ask if they wanted to borrow a suit, and of course they all want to go into the pool once they see it."

Among the most unusual home swimming arrangements is Dr. Augustus Owen Godette's underground pool, which is entered through his basement. Only the pool's three skylight bubbles can be seen outside the house, from the garden.

"I wanted something we could use all year, and I heard about this from one of the patients," said Godette, who is a gynecologist and assistant professor at Howard University School of Medicine.

He explained that the builders dug the hole for the pool and inserted fiberglass bubbles, then surrounded that with foam insulation and completed the structure by pouring concrete. From his basement TV room, he opens a door to a short hallway that ends in a small exercise room. Another door opens to an approximately 10-square-foot platform. In front of the platform to the left is a whirlpool tub; to the right are steps leading into the pool.

The water is unformly 5 feet deep and the only standing area is at the entrance end. Because the pool is indoors it collects no leaves or dirt. The sides are bright orange and yellow and the skylights bring sunshine into the room. Splashes and voices echo, and the effect is like swimming in an underground cavern.

"People think it looks like something from outer space," Godette said with a chuckle.