I’ve checked and it seems you are covered for most things. White water rafting “up to Grade 4”; and “accompanied” scuba diving “up to 30 metres”.
There are no dolphins anywhere near Queenstown!
A side trip to Hammer Springs (north of Christchurch) might be worth considering.
Mama says there’s an agreeable 12 mile walk in Queenstown, taking in local gold hot spots, with, she claims, an odds on chance of becoming a millionaire, should you wish to avail yourself of the opportunity to pluck raw nuggets from the ground where others have simply failed to notice them.