Overview

20 Mile is a spot at the mouth of the 20 Mile River in Turnagain Arm, south of Anchorage, Alaska. Turnagain Arm is famous for having one of the highest tidal ranges in the world (up to 12 meters/40 feet) and its spectacular bore tide. Winds are channeled and accelerated through the narrow arm, blowing primarily from the NE or SW depending on conditions. This spot is EXCLUSIVELY reserved for expert riders due to extreme conditions: deadly tides, glacial water, and devastating currents. The setting is grandiose with the Chugach Mountains as a backdrop.

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Spot forecast for 20 Mile

Sunrise 08:51 · Sunset 18:29

Open-Meteo

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< 7 kn7–12 kn13–20 kn21–30 kn31–40 kn41+ kn Gusts Your minimum: 7 kn

Forecasts provided by Open-Meteo

Swell and waves

Swell and tides over 8 days. Premium members see the swell and tides over 8 days. Without a subscription: 5 days.

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Wave height: < 0.5 m 0.5–1 m 1–2 m 2–3 m ≥ 3 m

Swell data by Open-Meteo Marine

Tides

Heights above lowest astronomical tide, in the spot's local time. Computed 18.8 km from the spot.

Tuesday 20 October High tide 02:46 · 9.1 m Low tide 09:04 · 3 m High tide 15:32 · 9.3 m Low tide 21:33 · 4.4 m
Wednesday 21 October High tide 03:45 · 9.3 m Low tide 10:01 · 2.9 m High tide 16:22 · 9.9 m Low tide 22:32 · 3.7 m
Thursday 22 October High tide 04:39 · 9.7 m Low tide 10:53 · 2.8 m High tide 17:07 · 10.5 m Low tide 23:24 · 3 m
Friday 23 October High tide 05:29 · 10.2 m Low tide 11:42 · 2.7 m High tide 17:49 · 11.1 m
Saturday 24 October Low tide 00:12 · 2.2 m High tide 06:16 · 10.6 m Low tide 12:28 · 2.7 m High tide 18:28 · 11.7 m

20 Mile: when to go?

Rideable days and hours computed for a minimum wind of 7 knots · log in to set your own (foil, twin-tip…)

Season · peak

2h

in July · 0.5 rideable days

The season runs from July to August, peaking in July: 1 rideable days a month and 2 hours of usable wind, at 18 °C. The low point is January, at 0 days.

Rideable days per month

Wind strength when it is rideable

7-12 knots · 100%

When the spot works, wind sits mostly between 7 and 12 knots — 100% of rideable hours. Big-kite territory. The coldest month is December, at -5 °C. The wettest month is January, with 447 mm.

Monthly averages: 20 Mile

Monthly averages — 20 Mile — averaged over 2 years of records — Weather data by Open-Meteo.com — How it is calculated
Month	Rideable days	Usable wind	Temperature	Rain
January	0.0	0 h	-3 °C	447 mm
February	0.0	0 h	-1 °C	204 mm
March	0.0	0 h	2 °C	238 mm
April	0.0	1 h	5 °C	305 mm
May	0.0	0 h	9 °C	234 mm
June	0.0	0 h	16 °C	132 mm
July	0.5	2 h	18 °C	121 mm
August	0.5	2 h	17 °C	129 mm
September	0.0	0 h	13 °C	283 mm
October	0.0	1 h	6 °C	344 mm
November	0.0	0 h	-1 °C	265 mm
December	0.0	0 h	-5 °C	297 mm

Photo gallery of 20 Mile

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Technical details of 20 Mile spot

The spot works with winds from NE, ENE, SW, WSW.

Rideable Not rideable

Spot opening date · Required level

Spot opening date: Open all year round
Required level: Expert

On the water

GLACIAL water year-round (2-10°C/36-50°F) — dry suit ABSOLUTELY MANDATORY. EXTREME tidal range up to 12 meters/40 feet — one of the highest in the world. The bore tide can create a 2-meter wave traveling at 15+ knots up the arm. The bottom is glacial mud — EXTREMELY DANGEROUS: this mud can trap a person like quicksand. Water is glacial, turbid, and sediment-laden. Tidal currents among the strongest in the world.

Hazards

AMONG THE MOST DANGEROUS SPOTS IN THE WORLD. Glacial mud = quicksand — people have DIED trapped in Turnagain Arm mud waiting for the rising tide. NEVER walk on the mudflats. 12 m tidal range — the tide rises faster than a person can run. Bore tide potentially fatal. Glacial water — fatal hypothermia in minutes. Devastating currents. Brown bears and moose on the shores. Alaska Railroad trains along the coast. Floating debris (logs). Very limited rescue services.

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Webcams near 20 Mile

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Nearby spots

All spots: Alaska

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20 Mile kitesurf and wingfoil spot