The Big Four Ice Caves are a series of ice caves at the base of Big Four Mountain. The hike out to the cave is on an easy, well-maintained trail. The trailhead is at the former site of a three-story, fifty-room hotel that was built in 1920 and burned down in 1949. Only the hearth and chimney survived, both of which still stand in the present picnic area.
The hike begins on a boardwalk over a lowland marsh known to host beavers. About a quarter-mile down the trail, a shiny new aluminum bridge spans the South Fork of the Stillaguamish River. It was constructed in 2009 after a 2006 storm destroyed the previous wooden bridge that had stood since the 1960s.
Signs warn hikers of avalanche danger near the edge of the forest, and hundreds of downed trees are evidence of previous slides. There is very little risk in summer and fall, of course. After you've reached the clearing, the primary ice field will appear off to the southwest, and the secondary ice field is further down the trail to the north.
Icefall, rockfall, and collapses are common in the cave, and people have been injured and even killed on multiple occasions. The edges of the caves are the most susceptible to rock and ice fall, so use extreme caution while crossing the threshold if you choose to enter the caves. Additionally, be very careful as you pass under ice bridges, and do not attempt to cross an ice bridge.
Late summer and fall are the best times to visit the ice caves, as they are only exposed from August through October. This trail is one of the most popular hikes in the area, reportedly attracting around 50,000 visitors every year, so crowds should be expected. For a more solitary experience, this makes a wonderful sunrise hike.