Around 15km from Southport is Hastings Caves & Thermal Springs (parks.tas.gov.au; adult/child $24/12, pool only $5/2.50), a state reserve where you can descend into the half-light below conical Adamsons Peak on a 45-minute guided tour through Newdegate Cave – the largest (publicly accessible) dolerite cave in the country. Tours run hourly from 11am to 3pm on a first-come, first-served basis. Take a dip in the thermal pool afterwards.
The visitor center cafe sells toasted sandwiches and pies.
There's a good chance of spotting a platypus on the 10-minute Platypus Walk behind the pool, while the wheelchair-friendly Hot Springs Trail does a big loop from the pool area, taking 20 minutes to navigate (the pool is also wheelchair accessible).
Note that the cave entrance is a further 5km drive beyond the visitor center. No public transport runs out this way.
