Japan: The Izu Peninsula

The densest concentration of hot springs in Japan - about 2,500 - is found less than two hours from Tokyo on the Izu Peninsula. Protruding into the Pacific like a giant arrowhead, the Izu Hanto emerged over centuries from the lava flows of Mount Fuji. It comprises a mountainous backbone flanked by a string of fishing villages.

At the southern tip lies the biggest town, Shimoda, with 50,000 inhabitants - and it is here that the Odoriko ("dancing girl") express train from Tokyo terminates. As usual, it is packed with hundreds of Tokyoites keen to unwind by boiling themselves in steaming, volcanic spring water.

I found a minshuku (the Japanese equivalent of b & b) in the fishing village of Sotoura, a place with a slow, easy charm. The weather was on the turn, painted shutters slammed in a stiff breeze, and I seemed to be the only visitor apart from a handful of hardy types struggling with kayaks on the choppy waters of Sotoura Bay. After an energetic tramp around the hilly streets, and with a busy week behind me, I was ready for the onsen (hot springs) experience.

I headed for the thermal waters in the one-street village of Rendaji (part of the traditional Kanaya ryokan, or inn). Some theories link the origins of onsen with ancient Buddhist purification rites, and it's certainly true that visiting an onsen involves an element of ritual.

The woman who welcomed me at the door kindly explained everything I needed to know in Japanese before handing me an oshibori (tiny towel) and leaving me to it. I'd managed to grasp the bit about putting all my clothes in the wicker basket, but as I dithered around the changing rooms my gaze kept straying back to the pair of doors leading through to the baths: one side for men, and one for women. If I called this one wrong, I'd probably make the evening news.

With nothing but the towel for back-up, I made my choice and stepped through. As luck would have it, I was in the men's section of the ofuro, or indoor bath. My sense of relief, though intense, swiftly evaporated as the heat closed in around me. True connoisseurs of onsen can languish in these places for hours, but as I sank gingerly into the green water - having taken my cue from the locals and washed first at the taps around the edge - I knew I wouldn't last. In the stifling humidity, I reckoned I had a matter of minutes before either getting out or passing out.

A fellow bather noticed my unease and indicated that I should place the oshibori on my head. The tip certainly helped, enabling me to settle against one of the floating log headrests and take time to appreciate the beautiful cedarwood surroundings, the tasteful arrangement of classical statues and the flawless domed ceiling above. At 109F (43C), the water was deeply soothing, and the knowledge that the minerals of this particular onsen were actively combating skin complaints, rheumatism and neuralgia only increased my sense of contentment. Drowsily, I noticed that a few women had drifted across to join their husbands; my earlier qualms had been for nothing.

Later on, with all modesty forgotten in the companionable atmosphere of the outdoor rotenburo pool, I got chatting to a group of young holidaymakers from Nagano. With the rain teeming down around our heads, they outlined the extent of geothermal activity that supports thousands of such resorts across Japan: according to one of them you could, given the time, visit a different onsen every week for 40 years. Since they come in endless variations, you'd certainly never get bored - there's even a famous hot springs near Jigokudani shared by hundreds of laid-back macaques.

Having slightly overdone things, I clambered out on legs of jelly. Experienced bathers normally dip into the cold plunge pool before leaving, but in my light-headed state I spurned this critical step and as a result hadn't cooled down properly when I arrived back at the minshuku hours later.

The landlady took one look at my scarlet face and decided I was coming down with a fever. A hot bath would do me good, she said.