NEW YORK — How would you like to sleep in a treehouse? Perhaps you'd prefer a tent inside a volcanic crater, or a prison cell.

These are some of the unique options found at www.hostelworld.com, which also lists conventional accommodations — both dorm-style and private rooms — at hostels around the globe. The Web site's 10 most exotic hostels:

Kadir's Tree Houses, in Olympos, Turkey, where you can choose from 45 tree houses, as well as bungalows and a campsite, for a mere $8 a night.

Hedonisia Hawaii, on the Big Island, offering dorm-style tent accommodations inside a huge volcanic crater with a mini-jungle at the bottom, $20.

Navalhill Backpackers, in Bloemfontein, South Africa, a hostel in a nature reserve, $13 a night.

Beagle Houseboat, in Amsterdam, near the Heineken brewery and red-light district, $49 a night.

Slane Farm Hostel, in County Meath, Ireland, a working farm, starting at $25 a night.

Gram's Place Bed & Breakfast/hostel , in Tampa, Fla., where one of the rooms is a sleeper car from a train, starting at $20 a night.

Seashell Cove Resort, Nadi, Fiji, private beach bungalows and dormitory accommodations, starting at $23 a night.

Hostel Celica, Ljubljana, Slovenia, a former prison that has been turned into an art gallery, with bedrooms that are decorated as individual works of art, starting at $21.

ZicZac Rock-Hotel, Zurich, Switzerland, where each of the 50 rooms honors a rock legend (like the Led Zeppelin Zuite), starting at $48 nightly.