The Otehake hotpools can be found in Arthurs Pass and make a great overnighter. They're about 7 hours drive from Dunedin which is a bit of a bummer, but if you're around Christchurch they're a lot closer.
The track starts by the Taramakau River, which in normal conditions is easily fordable. A flood bridge exists upstream but it will add an hour or two onto the walk. The beginning of the track crosses easy-going farmland for an hour before turning off up towards Lake Kaurapataki via the dry looking Pfiefer Creek. The track eventually goes into the bush before passing by the lake and some nice campsites. It then follows the lake shore around, then cutting up and over a spur and down to the Otehake river. On the spur there is a signpost to the old bridge, from here it is an hour or so to the hotpools up river. The descent to the river involves a bit of cliff scrambling and a section that turns into a waterfall in heavy rain. Once beside the river it is another k and a half before the hotpools can be found hidden in a bend in the river on the other side. This involves another river crossing and so it is important to be aware of the weather forecast as to not get stuck. There is amble camping spots on the river side of the hotpools. All in all it takes around 3 hours to walk to the hot pools and maybe half that to get back to the carpark.