The perimeter of the lake is approximately 18.5 km with an average depth of 10 m. The lake is primarily spring fed and supplemented by creeks and seasonal run-off. Ril Lake is located in the Precambrian Shield area of northern Ontario, consisting of underlying granite bedrock overlayed with 1.5 to 6 m of soil, often with rocky granite outcroppings.
The north-eastern area of the lake is more developed with lots ranging from 15 to 30 m of waterfront and developed shoreline. The south-western area of the lake is less developed with lots ranging from 120 to 915 m. Ril Lake is designated as a "Category 2" lake by the Province of Ontario, reflecting its sensitivity to environmental damage and placing restrictions on future development.
Local forest is a mix of deciduous and conifer trees. Local wildlife includes; turtles, deer, moose, beaver, bear, fox, otter, racoon, turkey, and porcupine. A wide range of bird species are known to frequent the lake including; loon, heron, owls, ducks, raven, and woodpeckers. The fish population is made up of mostly small and large-mouth bass.