The Tasman Lake is one of three glacial lakes easily accessible from the White Horse Hill campsite in Mount Cook National Park (the others being Mueller Lake and Hooker Lake). A ten minute drive from the campsite, the paved road goes almost to the lake’s edge.
From the car park there are several short trails – taking up to about 15 minutes – which lead you to lookup points over the lake and towards the glacier. On a clear day there are excellent views of surrounding peaks, including the east side of Mount Cook. There is also the chance to see icebergs floating in the lake below. Several small lakes – called the Blue Lakes, but actually green – can be accessed via small side trails.
Perhaps the most obvious sight at these viewpoints is the massive loss of ice the Tasman glacier has suffered over recent decades. The sheer height and depth of the moraine debris graphically highlights the speed of this retreat. In fact, the aforementioned Blue Lakes did indeed use to be blue – in a time when the glacier was much higher and much closer, and its melt water fed them. Now fed only by rainwater, the lakes’ colour has changed.
The Tasman car park is also the starting point for a more strenuous and interesting trek along the West side of Tasman Lake, towards Ball Hut (called the Ball Shelter track on some maps). Experienced hikers can take the trip even further, ascending to the privately owned Caroline Hut. There is even a route up and over Ball Pass, which descends to the Hooker Valley – although recent reports I have read about this route suggest the descent into Hooker valley may be impassable on the Hooker Valley side due to land slips.
As always, the information provided by New Zealand’s Department of Conservation is excellent, with trail guides and clear maps.