Mount St. Helens

On 18 May 1980 an earthquake triggered the largest landslide in recorded history, which uncorked the pressurised system beneath and produced a lateral blast that flattened about six hundred square kilometres of forest in minutes and killed fifty-seven people. The summit dropped from 2,950 to about 2,549 metres and the north side became a horseshoe crater. What was done afterwards matters: much of the blast zone was set aside in 1982 as a national volcanic monument and deliberately left unplanted, so ecologists could watch primary succession from bare ground - one of the longest-running such studies anywhere. Johnston Ridge Observatory looks directly into the crater; access has been affected by road damage in recent years.

What you actually see

• A horseshoe crater - where four hundred metres of summit went.
• The blast zone - flattened forest, much of it left unplanted.
• Ongoing succession research - running since 1982.
• Johnston Ridge - looking straight into the crater, when open.

When to go

June to October; the road is closed by snow in winter. A full day.

Honest expectations

Road damage has closed access to Johnston Ridge for extended periods - check before travelling. Cloud hides the crater often. Summit climbing permits are limited and required. The mountain remains active.

Nearby

Ape Cave lava tube is on the south side; Portland is south.