[6] Precipitation runoff from Flattop Peak drains east into Bugaboo Creek which is a tributary of the Columbia River; as well as west to Duncan River via East Creek.

Flattop Peak is more notable for its steep rise above local terrain than for its absolute elevation as topographic relief is significant with the summit rising 1,660 meters (5,446 ft) above East Creek in 3 km (1.9 mi).

The nearest higher neighbor is line parent Howser Peak, 1.21 km (0.75 mi) to the southeast.

[2][3] The peak's descriptive name was applied by Eaton Cromwell, who made the first ascent of the summit with Peter Kaufmann on August 10, 1930.

[1][6][7] The mountain's toponym was officially adopted on June 9, 1960, by the Geographical Names Board of Canada.