Wales - Skomer Island
The secret is out about Skomer — among birds, anyway. Nearly half a million puffins, kittiwakes, fulmars, and razorbills build nests in the lichen-covered cliffs of the 721-acre nature reserve off mainland Wales. The birds far outnumber the dozen or so humans on Skomer, just a 15-minute ferry ride from the town of Martin's Haven. The island is protected by The Wildlife Trust of South and West Wales. A maximum of 250 people may visit per day, but there's only room for 15 overnight guests in a converted barn. If you visit between May and July, when the majority of birds are nesting, you'll hear the eerie serenade of the rare Manx shearwater; there are more than 200,000 of them on Skomer.

Nicaragua - Corn Islands
Forty miles off mainland Nicaragua, the Corn Islands are still populated by the descendants of buccaneers. On Great Corn Island — one-hour La Costeña flights depart daily from Managua — the only attractions are sand and sea, including a reef that surrounds a 400-year-old Spanish galleon. Great Corn is a metropolis compared with the 1.4-square-mile Little Corn Island. The $6 ferry from Great Corn drops you off near the two best places to stay: Hotel Los Delfines and Casa Iguana, which relies on solar power because of spotty electricity.

Greece - Kíthira Island
Mythical characters dwell everywhere on Kíthira, just eight miles off the tip of the Peloponnesian peninsula. Here's the pool where Aphrodite bathed. Over there, you can see the cave where Helen and Paris are believed to have sought refuge. Except for the six weeks starting in mid-July, Kíthira is a sleepy place with compact medieval villages that are home to ancient grain mills, Byzantine chapels, and cheerful wooden beehives that are painted yellow, blue, or white. (Kíthira's thyme-scented honey is so coveted that the annual production sells out within weeks.) An even better base for exploring is one of the villages in the center, such as Mitata, where a beekeeper has opened Aplinori, an inn where guests can learn how to make honey and cheese.

Australia - Rottnest Island
The island has more than 60 white-sand beaches. Dutch explorer Willem de Vlamingh, who discovered the island in 1696, mistook the marsupial quokkas for rats, and named the place "rat's nest." The island, 12 miles off mainland Australia, has become a popular day trip from Perth. The best way to tour the salt lakes in the interior is to rent a bicycle through Rottnest Bike Hire. The reefs around the island are great for snorkeling; Oceanic Cruises leads excursions to shipwrecks off Kingston Reef. Most visitors come just for the day, but there are lodgings—cabins and bungalows managed by the island authority. Before heading back to catch the ferry, stop for some Victoria Bitter beer and a platter of fish, scallops, and oysters at the Rottnest Tearooms Bar & Café.

French Polynesia - Fakarava Island
In the center of Rotoava village is the Relais Marama, the one pension in town with oceanfront bungalows. For divers and snorkelers, the northern Garuae Pass and the southern Tumakohua Pass have pristine coral reefs that are accessible through outfitter Te Ava Nui. You'll have to travel for a full day to get to and from Tumakohua — the pass is only reachable by boat. The nearby village of Tetamanu has a church built entirely out of coral, as well as several black-pearl farms that give free tours. A pension on the outskirts of Rotoava, Pearl Guest House Havaiki, will even allow you to snorkel to its oyster farm with the owner and keep any pearls you find.

Indonesia - Sumba Island
The natives' reputation convinced European traders to avoid the island in southern Indonesia, leaving it relatively undeveloped for centuries. The warrior culture lives on in the annual Pasola ritual war festival held each February and March, in which horsemen from various tribes joust using spears. For more mellow activities, the island's southern coast has great surfing — 12-foot swells are not uncommon — and a community-minded (although expensive) resort called Nihiwatu. The hotel has day trips to nearby villages, where you can chew betel nut with the locals, buy colorful ikat cloth, and volunteer at a clinic funded by the resort.

Peru - Amantaní Island
Few places have a welcoming committee quite like the one on Amantaní, an island in Lake Titicaca: Aymara Indian women wearing embroidered black tunics line the dock and wave to visitors as they disembark from the ferry arriving from the city of Puno. There are no cars or roads, and quinoa and barley are grown by hand — as they have been for centuries — on hillside terraces. Stone hiking paths lead to the island's two highest peaks, Pachamama (Mother Earth) and Pachatata (Father Earth). During the Fiesta de la Santa Tierra each January, the residents form dual processions from temples built atop Pachamama and Pachatata to the main village, also called Amantaní, where everyone dances late into the night.

See photos of these islands at BudgetTravel.com