The hike up to the summit was truly grueling but the view from the top was spectacular and definitely worth the aching legs.

Take a look around the crater

See a steaming fumarole

Volcan Turrialba is one of the highest volcanoes in Costa Rica, at  some 3,300 meters (over 10,000 feet). It last erupted during the 1860s and is currently dormant, though there is a great deal of fumarole activity around two of its three summit craters. A third crater, on the eastern rim, is the oldest, and now contains a marshy lake. Towering over the central highlands of Costa Rica,  Turrialba faces the capital city of San Jose from its west side, while the Caribbean Seacoast can be seen from the east side of the summit.

The flanks of Turrialba, an immense mountain, are covered at the uppermost reaches with lush tropical cloud  forest, while the mid- and lower-elevation flanks are home to extensive agriculture, the dark and rich volcanic soils providing excellent farmland and forage to dairy cattle. A single, tortuous dirt road switches back and forth up the west flank from the populated valley floor below, and this route leads to the Turrialba volcanic national park and natural reserve. The summit's crater rims are reached via a number of rugged trails by which visitors hiking in from the roadhead may descend into the yawning craters themselves. This was the final destination of our scientific party during the first full day of sampling activity planned for this Volcano Expedition.

After an exhausting, two-hour hike up the mountain and into the craters, Dr. Hilton and his multinational group of scientists and journalists began taking samples of fumarole gases. Hilton reports:

We looked down into the central crater and wondered how to get down there. Guillermo led the way along a tenuous path along the crater rim until a route to the central crater opened up.  It took about half an hour to get down there, and we were greeted by the familiar whiff of sulphur dioxide a characteristic gas emanated from volcanoes, and a dangerous one if too much is inhaled.  It came from a plethora of mildly-venting fumaroles lined up on terraces along the crater wall.  We had our first target and we sampled these vents using our evacuated flasks.

However, further up the crater wall beyond a saddleback separating the west and central craters, there were indications of additional fumaroles that were even more active.  Toby took the lead in scurrying up there, and was rewarded by discovering a large field of fumaroles venting vigorously at about 90^oC the boiling temperature of water at the altitude of Turrialba (10,000+ feet).  Alison joined Toby in the haze of the fumarole field and they duly collected a number of samples.  Fortunately, Toby's Christmas gift of walkie-talkies allowed us to keep in touch with him and Alison the whole time even though they disappeared from view.

Finally Guillermo pointed us to some dark volcanic bombs which were thrown out of the crater during the last eruption of this sleeping giant 135 years ago.  The bombs contained tiny green crystals of olivine which trapped the volatiles in their mineral structure.  Seeing the products from the last eruption ended a memorable day on Turrialba and though our legs were shaking all the way down the volcano we will remember the awesome fumaroles and look forward to getting these samples back to the lab.