Thunder Lake is located 6.6 miles from the Wild Basin Trailhead in Rocky Mountain National Park. It lies just below treeline in an open basin with excellent fishing and numerous backcountry campsites. This long but moderate trail follows North St Vrain Creek through dense forest with stops at Copeland Falls, Calypso Cascades and Ouzel Falls. A well-defined route continues past Thunder Lake to Boulder Grand Pass (12,061') on the Continental Divide, which can be navigated down to the East Inlet Trail to form one of the most challenging E-W thru hikes across the Park.

Thunder Lake is one of several subalpine and alpine lakes that form the headwaters of North St Vrain Creek, the primary drainage through Wild Basin

The main trail runs along Thunder Lake's north side to the inlet area, and continues on a variously steep and rugged path to Boulder Grand Pass on the Continental Divide

Black bears are active in the Wild Basin Area, and food storage guidelines are strictly enforced

Thunder Lake's outlet stream forms large pools and slow oxbows through a level, marshy basin

Breaks in the timber reveal peaks above Eagle Lake and Frigid Lake, located along trail-less tributaries of North St Vrain Creek

Pilot Mountain (12,222') and Alice Mountain (13,310') frame the upper valley and separate the Thunder Lake and Lion Lake basins

Falcon Lake (11,070') is located below Pilot Mountain (12,222') in a small cirque about .7 miles from Thunder Lake's inlet area

Globe Flowers' scientific name is Trollius albiflorus; 'troll' means 'globe' in Latin

Colorado subalpine forests typically range 9,000' - 11,000' with primary constituents of subalpine fir and Engelmann spruce

The cross-country route to Falcon Lake climbs 500' from Thunder Lake, with only one steep section just below the cirque

Calypso Cascades forms just below the confluence of two major tributaries of North St Vrain Creek

Ouzel Falls is named for the Ouzel - or American Dipper - North America's only true aquatic song bird

The Calypso Cascades bridge was spared from damage in the 2013 floods (the Ouzel Falls bridge was not so lucky!)

Swift water between the two main Copeland Falls viewing areas just beyond the trailhead

Ouzel Falls slip through a narrow granite chute just off the main trail, where social paths lead to various viewing areas

On the way to Thunder Lake, Ouzel Falls (seen here) is a popular day hike for visitors short on time

Final approach to Thunder Lake

View of the lake from its beautiful outlet area

Thunder Lake has a clearly defined outlet stream - a great place to explore

Snow lingers well into deep summer, sometimes never melting