The 8.1 miles of the Fox Glacier in New Zealand's Westland Tai Poutini National Park form an ever-transforming terrain of ice caves and glacial terminal that is bordered on all sides by rainforests and mountains. 

Along with its neighbor Franz Josef Glacier, it's one of the world's most accessible glaciers for exploring, and regular guided tours are available. The glacier has been advancing since 1985 after decades of retreating, and with all the movement and melting stunning ice caves have been revealed. 

However, gorgeous as it is, solo wandering is not allowed as there is a danger of ice breaks and rockfalls that in the past have proved fatal.