About This Route
Grinnell Glacier Trail leads to Grinnell Lake, a turquoise gem in Glacier National Park's Many Glacier area, ideal yet risky for swimming. This 10.6-mile round-trip (or 7.6 miles with boat shuttle) climbs 1,700 feet from Grinnell Glacier Trailhead near Swiftcurrent Lake. Pass Upper and Lower Grinnell Falls before reaching the iceberg-dotted lake beneath Grinnell Glacier. NPS notes extreme cold (often 40°F or below) and recent glacial retreat increasing rockfall; swimming is allowed but demands caution. Thrill-seekers brave the chill for photos, but slips into deep water have led to rescues. Adhere to Leave No Trace by using established paths and avoiding glacial ice disturbance.
Safety Considerations
Per NPS water safety guidelines, frigid glacial melt causes hypothermia rapidly; symptoms include shivering and confusion within minutes. Icebergs calve unpredictably, creating waves and suction hazards. Mossy shores and log jams amplify slip risks, particularly near the outlet. Avoid swimming near the glacier face due to 15°F air temp drops reported on trails. Boaters note standing up risks capsizing; always wear PFDs. REI advises pre-swim warm-ups and 1:4 buddy ratios. Check Many Glacier Ranger Station for bear alerts and water levels; afternoon winds whip up whitecaps.
Essential Gear
Essential: O'Neill Mutant wetsuit (5/4mm); NRS Chinook PFD life jacket; Astral TR1 water shoes; Osprey dry sack; emergency bivvy (SOL); layered merino base (Smartwool); Glacier Park bear spray; UV-protective rash guard.
Emergency Tips
For cold shock, float on back to recover; hypothermia treatment mirrors NPS: skin-to-skin warmth, hot drinks. Contact Many Glacier Rangers at 406-888-7800; use trailhead satellite phone if signal fails.