A water park in the middle of the city might conjure thoughts of tourists and hordes of unruly children, but at Spa Castle in the College Point section of Queens (a stone’s throw from Flushing), the patrons are largely grown-ups, and the sprawling square footage means never having to jostle for space with the out-of-towners.

POOLS

Once known as Inspa World, Spa Castle advertises itself as both a spa and a water park. But it is essentially a jimjilbang, or Korean bathhouse, featuring a gym, indoor and outdoor pools, and aquatherapy in the form of whirlpools (heated and cool) and saunas. In contrast to its counterpart in the tristate area, the King Sauna in Palisades Park, N.J., Spa Castle also boasts a load of spa treatments such as waxing, facials, manicures and pedicures, body wraps and mud treatments, and massages; prices range from $15 for a manicure to $130 for a massage, and making reservations two days in advance is recommended. A food court serves up sushi, salads, assorted yogurts, and waffles for the post-massage bouts of hunger.

Admission to the spa ($35 weekdays; $45 weekends) requires a mandatory shower in the facility’s large bathing quarters. There, visitors will find both sit-down and stand-up showers separated according to gender. After cleaning up, customers are given a spa-issued uniform of T-shirt and shorts, and a locker to store valuables.

While roaming the five-story facility, visitors should make a stop on the fourth floor, where the outdoor heated pools are typically the main attraction for the local Korean families, groups of Eastern European men, and adventure seekers of all nationalities who come to tumble or relax along the pool jets. These jets promise maximum massaging comfort. If that doesn’t ease your tension, the in-pool bar offers refreshing warm-weather drinks.

TRAVELING

Driving is probably the easiest way to get to Spa Castle (131-10 Eleventh Ave. at 131st Street, College Point, Queens, 718-939-6300): From Manhattan, take the Van Wyck Expressway to Exit 15. But it is also accessible by public transportation — and a little walking. The 7 train to the last stop, Main Street, Flushing, takes riders to the Q20B bus, which stops directly in front of the Macy’s department store (136-50 Roosevelt Ave., between Main and Union streets). Take the Q20B to 132nd Street and Fourteenth Avenue; the spa is just a few blocks away on foot.

In addition, Spa Castle provides free shuttle bus transportation from the Flushing Municipal Parking Lot (at Union Street and 39th Avenue), departing twice every hour on the 10- and 40-minute marks. Another bus leaves at the top of every hour from Flushing’s Han Yang Supermarket (150-51 Northern Blvd. at 150th Street).

For more information, including a list of all spa services, go to nyspacastle.com.