Group reservation system takes effect at Whiteoak Sink A photographer frames a close-up shot in Whiteoak Sink. NPS photo A trial reservation system for group access to the Whiteoak Sink area in the Great Smoky Mountains National Park will go into effect for the 2021 wildflower season, April 12-30. Group leaders can make reservations at www.recreation.gov for a special park use permit to access the area with groups of eight to 12 people. Leaders can reserve a morning permit for access from 7 to 10 a.m. or an afternoon permit with access from 2 to 5 p.m. A fee of $50 is required for each permit, along with a $6 reservation fee, and these payments can be made online at the time of the reservation. Group leaders may reserve two permits per season.