Natural anchors

Natural anchors are often the strongest, cleanest, and most intuitive anchors you can build — but only if you evaluate them correctly. Many climbers overtrust large objects without assessing the medium (soil, rock, root system) that holds them in place.

This article teaches a clear, modern approach for deciding whether a natural feature will truly hold, and how to rig it efficiently.

This video shows how to make a top rope anchor using two trees and using a single static rope with a bowline and a bowline on a bight.

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Overview of natural anchors

Why natural anchors matter

Natural anchors allow you to:

• Save gear for the climb
• Build rapid, clean anchor systems
• Create extremely strong points of protection
• Reduce hardware use in fragile environments

A natural anchor is only as strong as both the object and the terrain supporting it.

The two-part evaluation framework

Every natural anchor must pass two tests:

• Object Strength: The tree, boulder, or rock feature itself must be solid.
• Foundation Strength: The soil or rock around the object must resist the expected load direction. Most natural-anchor failures occur in the foundation, not the feature itself.

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Tree Anchors

Trees can make excellent anchors when evaluated properly.

Evaluating a Tree

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Common Failure Modes

• Uprooting in shallow or loose soil
• Bending failure from high trunk loading
• Trunk shear from rot or internal cavities
• Soil shear where the ground fails before the tree does

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How to tie a bowline around a tree

1. Wrap the tree: Pass the rope around the tree so both ends hang next to each other. The side going back to your anchor system is the standing end; the free one is the working end.
2. Make the “hole” In the standing end, tie a small loop by twisting a bight so the standing part lies on top of the loop.
3. Rabbit comes out of the hole: Take the working end and poke it up through the loop you just made.
4. Around the tree (the standing part): Wrap the working end around the standing part of the rope (coming from the anchor).
5. Back into the hole: Bring the working end back down through the original loop.
6. Dress and tighten: Pull the standing end and the loop around the tree to snug everything up. Make sure the knot is neat: the loop should look like a “P” and not be crossed or twisted.
7. Finish with a stopper: Tie a backup overhand in the working end around the standing part, snugged tight against the bowline.

Advantages:

• No sliding
• Minimal wear
• Works on all trunk sizes

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Girth Hitch (Use Selectively)

• Use only when a full wrap is impractical.
• Higher wear and increased friction on sling.
• Prefer nylon slings over Dyneema.

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Rope Wrap (Efficient for Alpine or Multi-Pitch)

1. Wrap rope around tree.
2. Tie overhand or figure-8 on a bight.
3. Clip as master point.

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Wrap the tree as low as possible:

• Reduces leverage forces
• Loads the strongest part of trunk + root structure

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Boulder Anchors

Boulders can be exceptionally strong if they are immobile and well seated.

Evaluating a Boulder

Immobility

• Push, pull, and kick test.
• Listen for shifting or hollow sounds.

Foundation Stability

• Embedded into soil or bedrock = good.
• Sitting on loose dirt, leaves, or pebbles = bad.

Shape Retention

• Prefer constrictions, notches, or low points.
• Smooth rounded boulders may require double wraps.

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Horns, Pinnacles, and Natural Rock Features

Evaluation

• Ensure the horn is part of solid bedrock.
• Avoid hollow, fractured, or thin features.
• Beware sharp edges contacting the sling.

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Rigging Horns

Double Wrap (Best)

• Minimizes sliding and increases surface area.

Basket Hitch

• Useful for large, rounded horns.

Girth Hitch

• Acceptable only for large, solid features.

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Redundancy in Natural Anchors

Redundancy is recommended when:

• Soil is soft or wet
• Load direction varies
• The anchor will take a dynamic load
• You feel any uncertainty

Good combinations:

• Tree + gear
• Boulder + horn
• Two natural features with independent foundations