Swimming is not recommended in Milford Sound due to its extremely cold temperatures and strong currents. The water in Milford Sound is glacial, which means that it is extremely cold, even in the summer months. The water temperature rarely exceeds 10°C (50°F), which can lead to hypothermia and other cold-related illnesses in a matter of minutes.
In addition to the cold temperatures, the currents in Milford Sound can be strong and unpredictable. The tides and currents in the Sound can create dangerous underwater currents that can be hazardous to swimmers and even experienced divers.
Despite the risks, there are some tour operators that offer kayaking or small boat tours that allow visitors to get up close to the waterfalls and cliffs that line the Sound. These tours provide life jackets and wetsuits to ensure that visitors are protected from the cold temperatures and currents.
If you are interested in swimming or other water-based activities, there are several other lakes and rivers in the Fiordland National Park that offer safer swimming options. Lake Te Anau, for example, is a popular destination for swimming, boating, and other water-based activities.
While it may be tempting to take a swim in the crystal-clear waters of Milford Sound, it is not recommended due to the extremely cold temperatures and strong currents. Visitors should stick to the various boat tours and kayaking options that are offered by licensed tour operators to ensure their safety and enjoyment of this stunning natural wonder.