I began this trip by kayaking across the first lake to the pay-boat-trip dock. One of the employees was nice enough to help me portage about 1/4 mile to the next lake. I launched there, and as I did, noticed the large group of people making there way back because of the grizzly bear on the trail. I found the grizzly bear and took several pictures of him (from the safety of my kayak in the water.) I made my way across the second lake and locked the kayak to a tree on the other side, close to the boat dock. I hiked the other 5 or 6 miles to the Grinnell Glacier and glacial lake. There were some really awesome views on the way there. On the way back, I floated the stream in between the lakes. It was a really nice trip with some really awesome views. I believe it was about 3 or 4 miles round-trip on the water and 12-15 miles on land. There is a nice little elevation gain, but I wouldn't call it a difficult trail or paddle. It's an easy paddle, except for the portage on the way there.
There is a really nice hotel and a very good campground within a hundred yards to the beginning of the trail and lakes.
You will either need the National Park Pass or pay the daily fee at the gate to enter.
Follow the road on the east side of Glacier National Park to Many Glaciers. You will see the turn for the hotel on the left. The first lake is there at the hotel. You will see the boat launch and parking about 100 yards past the road to the hotel. The campground is just past the boat launch.
The map that the Park Ranger gives you at the gate is very informative.