We are not organizing a central excursion, but there are various things you can do in and around Harrison Hot Springs:
Hiking
A good summary of very local hikes can be found here: http://http://www.tourismharrison.com/hiking#/gallery/recent
A have done a few of them myself, here are the links:
http://sportypal.com/Workouts/Details/4852146?key=299d3096660f78f2aea9a6f1937366e99acffce5&ms=0