GETTING THERE
Major carriers including American Airlines (www.aa.com), Japan Airlines (www.japanair.com), and All Nippon Airways (www.anaskyweb.com) fly nonstop daily to Tokyo's Narita and Osaka's Kansai airports from U.S. hubs. Except during peak travel times (late June–August and mid-December–early January), fares range between $600 and $800.

PRIME TIME
Spring, when cherry trees are blooming, and autumn, during the rice harvest, are your best bets for mild temps and stable weather.

GETTING AROUND
Take advantage of Japan's fast and reliable rail system. Except for subways and some local lines, most trains are run by Japan Railways (212-332-8686, www.japanrail.com). If you plan to travel between cities, the Japan Rail Pass is a good deal, starting at $250 for seven days. Highway buses (www.bus.or.jp/e) are a fine alternative, especially for the budget-conscious. Rental cars average $80 per day; make reservations online in English with Tocoo! Travel (www2.tocoo.jp/english).

EXPLORING
Beyond Tokyo: The town of Minakami, at the north end of Gunma prefecture, has emerged as a mecca for all-season adventure, with the steep slopes of Tanigawadake looming as its backdrop. For everything from canyoneering to backcountry snowboarding, contact Mike Harris at Canyons (011-81-278-72-2811, www.canyons.jp). Decompress at the natural hot springs of Osenkaku Ryokan ($84–$158 per person; 011-81-278-75-2611, www.japaneseguesthouses.com), a traditional inn with open-air baths overlooking the rumbling Takara River.

Surf's up at Chiba prefecture's Boso Peninsula, southeast of Tokyo, where the Pacific Ocean's warm currents hit miles of sandy beaches. In the town of Tateyama, on the southern tip of the peninsula, stay at American expat David Green's Hakkakuso Lodge ($84 per person, including two meals and bike use; 011-81-90-7716-0102, www.discoverjapan.co.jp), where you can grab maps and Trek mountain bikes for exploring the local trails.

The ancient capital of Kamakura, an hour south of Tokyo, has emerged as Japan's answer to Santa Monica, albeit with temples instead of retail promenades. The best view of the town's famed giant Buddha may be from the bay. Rent a sailboard from Seven Seas (011-81-467-22-5050, www.7seas.jp) and soak up the hospitality at the Kamakura Prince Hotel (doubles, $235; 011-81-467-32-1111, www.princehotels.co.jp/kamakura-e). IZU PENINSULA AND SEVEN ISLANDS: Avoid the summer traffic on the Izu Peninsula by paddling 125-plus miles of spectacular coastline. Splurge at Ikona ($165–$216 per person; 011-81-558-62-0030, www.royalparkhotels.co.jp), where you can get a room with its own outdoor spring-fed hot tub.

Ten hours by ferry (or two hours by hydrofoil) from Tokyo is Niijima, arguably the best surf spot in East Asia. Rent a bicycle with a surfboard rack near the ferry terminal. Yoshida-ya (011-81-4992-5-1661), where a room and two meals costs $60 per person, is one of about 50 lodging options on the island. NAGANO: Feast on what the mountains, rivers, and lakes have to offer with all manner of activities at Dave Enright's Evergreen Outdoor Center (011-81-261-72-5150, www.evergreen-outdoors.com). Climbers should head straight for Mount Ogawa (www.ogawayama.com), considered the best rock-climbing area in Japan. SADO ISLAND: Feed the seagulls at your own risk on the 2.5-hour ferry ride from Honshu. Freeway Diving (011-81-259-52-5781) will lead you past myriad deep-sea creatures to an underwater Buddha. Stay at Hana no Ki, a renovated 150-year-old farmhouse ($50 per person, including breakfast; 011-81-136-232-606, www2.ocn.ne.jp/~hananoki). Hokkaido: Ross Findlay's Niseko Adventure Center (011-81-136-23-2093, www.nac-web.com) delivers thrills in nearly every outdoor discipline, year-round. Walk to three ski areas in the morning and stumble home from the bars at night to Niseko Lodge ($64 per person, including breakfast; 011-81-136-232-606, www.nisekolodge.com). Shikoku: The historic Henro, a 900-mile walking pilgrimage to 88 temples, circles the entire island and makes for an epic bike tour. Or take a "shower climbing" journey through cascades, shallows, and falls with MontBell Outdoor Challenge guides (011-81-6-6538-0208, www.montbell.com). Kyushu: Rent bikes at Aso station, on the JR Hohi line, then switchback your way up Mount Aso, an active volcano. For extreme soaking, head to Beppu, a city with 104 onsen and mud and salt baths.

RESOURCES
The Japan National Tourist Organization (213-623-1952, www.jnto.go.jp) offers good information on its Web site, as does Japan-Guide.com. Outdoor Japan (www.outdoorjapan.com) is the most comprehensive resource for finding the Japan that's "out there." For places to stay, go to www.japaneseguesthouses.com.