We have been here numerous times over the years. This is one of the most scenic lakes to view in the Canadian Rockies. The really tough part about seeing this lake is the time of day. If you go first thing in the morning, there is hardly anyone there, however, the water is not the beautiful color you see in the pictures. To see that color you need to be there mid day and unfortunately that is the busiest time for this lake! The parking lot is always full in the afternoon, in fact it is so full, often you have to park at the side of the road if you are lucky enough to find a spot. Parks Canada doesn't like people parking on the side of the road.
Your best bet in seeing this attraction is to come mid morning and plan on staying for a while. There is a restaurant and hotel here with gift shop, so you can get a meal. There are trails around the lake as well, but as soon as the trails leave the lake, you have to be in groups of four or six (depends upon animal sightings - check with Parks Canada).
There is a great mound of rock at the top of the lake (this is where all the famous pictures are taken), There is great debate amongst geologists on how this mound got there, but for us, it is a great climb and easy to do. In fact Parks Canada revamped all the trails and steps in 2010 I believe.