A good stop for hikers visiting Washington State is a visit to the Big Four Ice Caves outside of Granite Falls ( an additional 26 miles along the Mountain Loop Highway).  The hike itself is a 1.1 mile round trip hike (short for the long trail hiker; but, the view is still worth the time) with an elevation gain of 200 feet (a very light slope) that ends at the base of Big Four Mountain where you can see ice fields and sometimes ice caves (during the spring).  One can enter the ice caves; but, remember that it is dangerous because these caves can collapse at any time, especially when the temperature start to get warmer.  Even if one does not enter the cave, the temperature difference between the inside and outside can be felt at the mouth.  For more information, please visit BigFourIceCaves website.