About This Route
Access Mills Lake via the Glacier Gorge Trailhead in Rocky Mountain National Park, a 5.4-mile round-trip hike to this 9,960-foot tarn below Longs Peak. Swimming is permitted (not restricted like Bear or Sprague Lakes), rewarding brave souls with breathtaking views of the Keyboard of the Winds cliffs. Snowmelt keeps waters icy; REI experts note peak swimming viability in late summer. The trail passes Alberta Falls, adding cascade mist to the adventure. Timed entry permits essential; shuttle recommended to avoid parking chaos.
Safety Considerations
Subzero wind chills possible despite summer air; hypothermia strikes fast in 40-degree water. Avalanche debris creates unstable shores; stick to NPS-designated paths. Rockfall from overhanging talus; swim away from cliffs. Altitude sickness symptoms emerge quickly above 9,000 feet; hydrate preemptively. Thunderstorms brew rapidly; descend pre-noon. No lifeguards; buddy system mandatory per US Coast Guard protocols. Post-swim, warm up actively to prevent afterdrop hypothermia.
Essential Gear
Full-body 5mm wetsuit (Patagonia R1 or Kokatat) for extended exposure. Insulated booties and gloves. Personal flotation device with whistle. Emergency bivvy sack (SOL brand). Trekking poles for trail stability, multi-tool, and UV-protective goggles against glacial reflection.