Yes, you need a valid parks pass to hike in Freycinet National Park. Hikers can purchase these online or at the Visitor Centre. If you get yours online, you still need to go to the centre to get a receipt to leave on your dash for the duration of the hike. For this multi-day hike I recommend a Holiday Pass (valid for up to 2 months) for $89.50 per vehicle or an Annual All Parks Pass for $95.30 (discounts for concessions and seniors).