Tommy Thompson Park's main access point sits at the base of the Leslie Street Spit, addressed as 1 Leslie Street near Unwin Avenue in Toronto — roughly five minutes east of the DVP/Gardiner junction along Lake Shore Boulevard East.

The entrance opens onto a man-made peninsula that extends five kilometres into Lake Ontario along the Outer Harbour Channel, built entirely from sand and silt dredged from Toronto's inner and outer harbours.

From this access point, visitors connect to an 18-kilometre trail network divided into multi-use, nature, and pedestrian trails.

A free parking lot sits approximately 40 metres west of Leslie Street, with additional street parking available on Leslie Street itself. Cyclists can reach the entrance via the Martin Goodman Trail, which links to the park on both its east and west sides.

TTC riders can take the 83 Jones bus southbound from Donlands Station to Leslie Street at Commissioners Street, then walk roughly eight minutes to the entrance.