Understand
Milford Sound is actually a fiord, having been carved by a glacier.
Like the rest of Fiordland, Milford Sound receives a lot of rain. Indeed, some tour operators argue that the sound is best seen on a rainy day as all the waterfalls can be seen in their full glory. Many recommend seeing it during a sunny day and in the rain to see both worlds as they are both very different and amazing
Wear rainwear and carry an umbrella to protect photographic equipment.
Bring bug repellant. The sand flies here are evil.
