The name and the setting of this lake is alluring. The lake is about 7 miles from the trailhead at Agnew Meadows. The trailhead is off the road down from the Minaret Summit which, during the summer months, has a vehicle restriction during certain hours - you have to take a shuttle bus. There are two main trails - the River trail and the High trail - which is the Pacific Crest Trail (PCT). The PCT route is much more scenic, with some great vista points over the upper Middle fork of the San Joaquin, the Minarets and the Banner and Ritter massif. The lake is at timberline and is a wonderful place to just sit and sun.
The trail ends at the shimmering blue lake, which, from the outlet, doesn't seem to merit its name (very few islands are visible). The scene is absolutely amazing, with Banner Peak, Mt. Ritter, the glaciers on Banner Peak, Mt. Davis, and Mt. Lyell rising above the lake. And the lake is so unbelievably, unbelievably blue. Walk southwest along the lakeshore for better views; the mostly flat trail leads to campsites, and on the way, there are many views of the island-dotted lake. And it does seem like there are a thousand. Eventually, Banner Peak will become more and more massive, Mt. Ritter will disappear, and the Minarets will come into view. The grassy and sometimes rock-lined lakeshore is always extremely photogenic; any picture taken here is a good picture.
A little over 7 miles past the trailhead, the trail comes upon a junction with the River Trail. At this point, both the River and High Trails end. The right fork leads uphill immediately towards Thousand Island Lake; after a short climb, the trail rounds a hill and views of Banner Peak and Mt. Ritter reemerge. The trail first winds through a small meadow with stunted pines, passes a sign prohibiting camping near the lake outlet, and then reaches a tiny, beautiful pond. Past the pond, the trail comes upon a verdant little valley of the Middle Fork San Joaquin River, with Banner Peak in the backdrop. This is an incredibly beautiful place, dotted with wildflowers and small pines. Continuing on, the trail rounds another small granite hill to a wide view of the lake's outlet, Ritter and Banner, and Mt. Davis and Mt. Lyell. The trail then descends to the windy lakeshore.
At Thousand Island Lake, you can fish, read, sun yourself or simply try and count all of the islands in the lake. Are there a thousand?