Geology of New Zealand Field Trip Guidebook - ResearchGate

Ruapehu Crater Climb—This is a five to seven hour walk, much of it across snow fields of
the Mt. Ruapehu Ski Area (Fig. 12). Our goal is to reach the summit crater of Mt. Ruapehu.
The crater contains an active, hydrothermal lake floored by molten sulfur! Outbursts from
this lake have produced destructive lahars throughout the volcano’s history. The lake is
closely monitored as a guide to Ruapehu eruptive activity. We will not descend into the
crater -- as Gollum would say, “Not nice! Not nice!” The water temperature is between 22-
25°C, which sounds pleasant until you remember that the pH is quite low and air-displacing
gasses like CO 2 and SO 2 are constantly bubbling from its surface. If the weather and the
mountain itself allow us to undertake this hike, we will do so under the supervision of a local
guide.
Figure 12: Ruapehu Crater Climb. Source: www.doc.gov.nz.
CAUTION: This is an exhilarating climb, but we will be moving through an area with
obvious and not-so-obvious hazards of which you must be mindful and for which you must
be prepared. First of all, be prepared as the weather can change quickly. We will not
undertake the climb unless the weather looks good, but conditions can change rapidly and
without warning. You should carry a warm hat, mittens, warm layers and a wind/waterproof
shell. I also recommend an extra pair of socks. Second, carry and drink at least 2 L of water
throughout the day. Since it’s cold, you don’t realize that you are perspiring and becoming
dehydrated, or you may feel shy about the possibility of urinating in an open snowfield. Get
over it! In 2003, one group of Ruapehu Crater Climbers didn’t drink enough and became
violently mountain sick (vomiting and headache comparable to the worst pub crawl of your
life—no fun). Third, protect yourself from the sun. The 2005 group returned from the climb
with some severe sun burns—especially to areas you would not expect. High altitude and
UV reflected off the snow pack led to sunburns on lips, the bottoms of noses, chins, etc. The
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