The fumes rising from Nicaragua's Cerro Negro volcano show that it's still rather active, and it's probably a good idea to make sure the makeshift sledge is facing the right way when you place it on the rim.
Ash-boarding is much the same as sandboarding, apart from with ash and pumice rather than sand, and volcanos being much taller than sand dunes. Clattering down the slope at up to 70km/h is a matter of hanging on for dear life as all manner of gunk flies at your face. It isn't half exhilarating, though. Vapues runs tours from León for US$28. ($34.).
Descend inside Thrihnukagigur, Iceland
Not content to let visitors hike up the side of a fire-breathing mountain, adventurous Icelanders have set up a cable lift inside the crater of the Thrihnukagigur volcano. You still have to schlep it up to the top, but once there, you're lowered 120 metres into the cathedral-like vault of Thrihnukagigur's magma chamber. Once inside, there's a chance to stroll around with headlamps, hoping not to hear any rumbling sounds. It's rather like being in a giant cave, but with an awful lot more red-charred rocks on the walls. Inside The Volcano runs tours for ISK 37.000 ($352).
Climb Mount Doom, New Zealand
The 19.4-kilometre Tongariro Alpine Crossing is a volcano adventure in itself, stretching across barren craters and past rusty red trickling hot water streams on New Zealand's North Island. But the epic day walk can be extended with an additional climb that's not for the faint-hearted. From Tongariro's south crater, Ngauruhoe rises up as a perfect – and massively intimidating – volcanic cone. It's so photogenic that it was used as Mount Doom in the Lord of the Rings films. But would-be Frodos should be aware that climbing it is a strenuous three-hour battle against treacherous rubbly slopes.
Mountain bike Haleakala, Hawaii
After heading to the 3055-metre summit of Haleakala and peering into the crater, there's only one way to go: down. Adventure Maui offers a tour that takes on the descent on two wheels, mountain biking 42 kilometres downhill to the ocean and stopping to shed layers of clothing on the way. The brakes get a proper workout, heading through lava fields, a series of switchbacks then finally the tropical sugar cane fields and pineapple groves. For those willing to brave a 2.30am start, it's possible to see the sun rise as part of the trip. Tours cost from US$104. ($127).
Journey from the centre of the earth, Ecuador
Mt Everest might be the world's tallest mountain, but the summit of dormant volcano Chimborazo is the furthest point (on land) from the earth's centre. This is due to the earth not being a perfect circle and bulging at the Equator. Chimborazo is one degree south of the Equator, with a 6267-metre elevation and 4123-metre rise above the surrounding landscape. It has not erupted for approximately 14 centuries, but don't expect an easy climb. A couple of days of technical training are needed before attempting the ascent through snow and ice. But, hopefully, not fire.
The American Alpine Institute runs five to 15-day expeditions for from US$1290 ($1582).
Trek to Lake Pinatubo, Philippines
Before 1991, Lake Pinatubo didn't exist. But then came an eruption that killed hundreds, blanketed the surrounding landscape in ash and changed global weather patterns. The top of Mt Pinatubo was blown off, and in time a crater lake settled in its place.
Getting there starts with four-wheel-driving through bleak, ash-covered landscapes, before a two-hour trek to the crater rim. The chalky surrounds get subtly more green the closer you get to the top – a sign that life is returning. Then the lake itself appears – looking irresistibly inviting, despite signs warning visitors not to swim in it.
Trekking Mount Pinatubo runs tours from Manila for from 2150 pesos ($59).
The writer was a guest of the Philippines Department of Tourism, Tourism New Zealand and Vapues Tours.