Canyon

Reference

The grading system

Every canyon topo carries a code like v4 a3 III. It looks cryptic but it is the most useful planning tool in the sport — three independent scales that together describe what a descent will ask of you.

The widely used European system rates a canyon on three axes. They are independent: a gorge can be steeply vertical but barely wet, or nearly flat yet deeply committing. Read all three together — never just the one that looks scariest.

v — vertical character

The technical difficulty of the descents: rappel height, awkwardness and exposure.

v1
Walking and simple scrambling. No rope needed.
v2
Easy down-climbs, the occasional short, simple rappel.
v3
Regular rappels on good anchors; straightforward rigging.
v4
Longer or more awkward rappels; some exposure and route-finding.
v5
Sustained vertical work; committing rigging and overhangs.
v6
Free-hanging, technical abseils demanding flawless technique.
v7
Extreme vertical terrain at the limit of the discipline.

a — aquatic character

How much the water itself is the obstacle: current, swims, hydraulics and siphons.

a1
Still or shallow water; no real current.
a2
Easy swims and gentle moving water.
a3
Noticeable current; swims that take effort.
a4
Powerful water, possible hydraulics; active hazard management.
a5
Violent water; serious risk from currents and recirculation.
a6
Extreme white water at the edge of what is survivable.
a7
Reserved for the most violent aquatic descents.

Roman numeral — commitment

The overall seriousness: length, remoteness and how hard it is to escape once started.

I
Very short; escape possible almost anywhere.
II
Short half-day; escapes available along the route.
III
Most of a day; limited escape options once committed.
IV
Long and committing; escape difficult, self-rescue essential.
V
Major descent; remote, long, no realistic escape.
VI
Expedition-grade commitment and remoteness.
The master variable. A modest v3 with a high commitment numeral can be far more serious than a steep v5 you can walk out of. Match a route to the weakest relevant skill in your group, and let the commitment grade decide how much margin for error you actually have.

Ready to put it into practice? Browse the spots directory, where every canyon lists its full grade.