Take the 1.5 hr walk around the lake to see the beautiful reflection of Aoraki/Mt Cook and Mt Tasman on its dark waters. The lake was formed during the last Ice Age retreat by Fox Glacier 14,000 years ago. The track is well maintained, and there are board walks and specially made platforms for getting the right angle for your pictures. The best light is at dawn, and it's about 20 minutes to the first lookout (and 20 minutes back if you don't want to walk the whole way) and 40 minutes to a floating pontoon.