The lake can be reached via two somewhat direct routes, both of which are predominately forest walks. The shorter, steeper route starts at the Foggy Dew Creek trailhead - found at elevation 3430 feet - and follows the Foggy Dew Creek Trail for 4.9 miles, then the Martin Creek Trail for 2.7 miles to reach the Cooney Lake Trail.
The longer, shallower route with a creek ford, starts at the Crater Creek trailhead, at elevation 4760 feet, and follows the Eagle Creek Trail for 2.2 miles, then the Martin Creek Trail, initially descending 350 feet for 6.4 miles to reach the Cooney Lake Trail (elevation 7240 feet). Once on the Cooney Lake Trail, it's only 0.2 mile to the lake. (The stated hike length and elevation gain here are for the longer route.)
The popularity of this area is evident in the many campsites around the northern half of the lake. The southwestern side of the lake is very marshy and the southeastern shore is fairly steep. Two large horse camps are in the vicinity of the lake with tether highlines at each.
Activities in the vicinity of the lake include fishing, swimming, and exploring. Exploration includes on trail (Cooney Lake Trail up to Switchback Pass and beyond to Angel's Staircase, Merchant Basin, or Sunrise Lake), abandoned trail (Martin Creek Trail to abandoned Foggy Dew Ridge Trail), or cross-country (in the basin to the southeast of Martin Peak or up informally named Switchback Peak).
The trails are usually snowfree in early July. At that time, the meadow to the north of the lake is beautifully flowered, but the mosquitoes are also flourishing. In the fall, the bugs are gone and the golden larch provide the bright contrast to green of the lake.
For solitude and quietness, this hike is best done mid-week. The multi-use Martin Creek Trail is only 0.2 mile away from the lake, so even though motorcycles are prohibited from the Cooney Lake Trail, their sound fills the lake basin as they pass by. Mountain bikers are quieter as they pass through on the Cooney Lake Trail section of the Angel's Staircase Loop.