Bordered on three sides by Interstate highways and on the other by rapidly encroaching real estate development, Eagle Creek Park sits as a tranquil oasis 12 miles from the hustle and bustle of Downtown Indianapolis.

At 5,200 acres, of which 1,300 is under water behind the dam that since 1967 has formed Eagle Creek Reservoir, it is the fourth-largest city park in the country — six times bigger than New York’s famed Central Park — and last year drew 647,000 visitors to the northwest corner of Marion County.

The park is home to weddings and business retreats. It hosts jazz concerts in the summer, hayrides in the fall and cross country skiers in the winter. Its Nature Center offers a variety of educational programs for adults and schoolchildren. But mostly, Eagle Creek Park is a quiet getaway for people looking to enjoy the outdoors while doing most anything or nothing at all.

“It’s in the city and yet it feels like it’s in the country,” said Stephanie Blockson, who on a recent weekday evening came to the park to jog with her husband, Jason, behind a double stroller carrying their two infant daughters.

Willie Shannon brings her wheelchair-using 76-year-old mother, Juanita Levi, to the park to fish from the banks of the reservoir. Once her mom is situated, Shannon uses the time to escape from the real world.

“I’ve got books, I take a nap, whatever,” she said. “I’ve been coming out here for years, and you can always find ways to entertain yourself while you’re here.”

Park manager Karen LaMere likes to call it “passive recreation,” which to her means enjoying the park in its natural state without paving it over to build basketball and tennis courts, or chopping down trees to build a recreation center, or suspending the rules to allow speedboats in the summer or snowmobiles in the winter.

“We’re a destination park, much like a national park or a state park,” she said. “We appeal to a broad use group, from birdwatchers to triathletes to picnickers to hikers and walkers to people who just want to be able to come here and enjoy the park with their family and friends.”

The land that now makes up the park, most of which sits between West 56th and 71st streets a mile west of I-465, was owned from 1936-58 by J.K. Lilly, who maintained it as a nature preserve.

The city originally declined an offer to turn it into a park because it was deemed to be too far in the country. Lilly donated it to Purdue University, which kept it until selling to the city. It opened as Eagle Creek Park in 1970.

The park’s size — “we like to point out we go through two ZIP codes,” park administrator Jeff Ward said — allows it to accommodate large weekend and holiday crowds without seeming crowded.

The north end is a bird sanctuary in which 265 of the 285 listed species in Indiana, including rare bald eagles and white pelicans, have been spotted.

The park has 11 miles of natural trails limited to foot traffic (cyclists are restricted to the roadways), 24 picnic sites and a pistol and archery range.

Dave Oakes is among the many triathletes who use the park as a training ground.

“It’s big and it’s open and it’s spacious and it’s clean,” he said. “I can come down here on the bike and get a little workout and then get a run in. It’s perfect.”

The reservoir is divided in half by the West 56th Street bridge, which is too low to allow large sailboats to pass under. The sailors stick to the south end while kayaks, canoes and pedal boats, available for rent at the park marina, stick to the north end.

Kayaker Kellie Kaneshiro likes being able to paddle without dealing with wakes from speedboats or personal watercraft.

“It makes it a lot more peaceful,” she said. “It’s great to be able to paddle and see the birds and all the other things you can see from the water that you can’t always see from the shore.”

Fishermen use both ends and don’t mind that their boats are restricted to 10 horsepower engines and 10 mph. Elwood Vance was smiling even after several hours of fishing that produced few fish.

“It’s nice here, it sure is,” he said. “You have to work for ‘em here, but that’s why they call it fishing, not catching.”

The Eagle Creek Sailing Club, located on the west side of the reservoir, has 275 members and 200 slips. It offers lessons and rentals and stages regular competitions through the summer, but club members like their relative isolation.

“A lot of people don’t know we’re back here, which is kind of nice for us,” Mike Gray said.

Gray doesn’t mind that the bridge slices the reservoir in half.

“It’s kind of nice to have that separation,” he said. “They do their thing and we do ours.”

Lack of rain this summer dropped the level of the reservoir several inches. Owners of larger-keeled boats had to pull them out of the water early. The sailing season typically runs from May to November.

Ed Rice, a member of the sailing club since 1972, waited last weekend for his son to join him for a leisurely afternoon. He said the unpredictable winds are the biggest challenge on Eagle Creek Reservoir.

“They say if you can sail on this lake, you can sail anywhere because the wind is so variable,” he said. “But it doesn’t bother me. I’m not going anywhere in particular anyway.”

Which pretty much sums up the whole idyllic experience of Eagle Creek Park.