Great option if you don’t want to do the full Tongariro Alpine crossing.

You can do part of it to Soda Springs instead! 9.5km return hike.

Beautiful scenery and well marked out path.

Approx 1hr to Soda Springs Waterfall

The walk up to soda springs is pretty flat with nice views. It's easy to carry on to red crater if you've got time and fancy a climb

The track starts from the end of Mangatepopo Road (a 4WD vehicle is recommended on this bumpy road with cracks). A carpark located a the trailhead is restricted to 4 hours from Labour weekend in October to the end of April.

https://www.doc.govt.nz/parks-and-recreation/places-to-go/central-north-island/places/tongariro-national-park/things-to-do/tracks/soda-springs-walk/

https://www.alltrails.com/trail/new-zealand/manawatu-wanganui/soda-springs-walk--2