Milford Sound is one of the wettest places on Earth: it rains >190 days out of the year, and last year they got more than 10m of rainfall (a heavier than usual year). We were lucky, and only had a bit of drizzle while we were there. The scale is a bit hard to appreciate: those mountains are >1000m high, according to the guide.

Because of the amount of rainfall and its shape, although the bulk of the water in the fiord is sea water, there is a layer of fresh water on top (as much as 6m).