North Sister

Castle Ravine holds a high spot on many bucket lists. However, a number of logistical challenges make it a hard one to check off. It's northern aspect is often scoured by the prevailing NW winds in the Whites, keeping conditions thin and crusty. It also only sees almost no sun in winter and just a few hours in spring, not to mention access requires a slog monster approach, no matter which direction you come from. With that being said, if you catch it in the right conditions, Castle Ravine offers some of the longest and most sustained steep couloirs in the range.

A number of approaches are possible, the shortest is to go from Castle Ravine Trail, however, this is hard to follow in the winter and crosses the river multiple times. A more reliable but taxing approach is to climb The Cog, then take Gulfside Path to Cornice Trail. Castle can also be combined with King Ravine for a lengthy linkup tour. 
      North Sister, also known as Twisted Sister, is arguably the most aesthetic line in Castle, with high rock walls guarding this steep couloir. The line begins with open turns down the couloir. A rock fin in the middle splits the line, with similar options to either side. Here the line steepens even more, clocking in above 40 degrees. Next comes the crux, a talus field that almost always has some sharks sticking out, even in the best snow years. Side slip your way through and join the run out. Even this is fairly steep and longer than it looks. Unlike most ravines that flatten at the bottom, Castle continues rapidly dropping vertical all the way to the river bed, making for a long, dramatic run. Continue down and cross the brook to Castle Ravine Trail, or switch to crampons and reverse your approach. Be aware that this is high consequence terrain and is extremely remote. If anything happens, such as a long sliding fall or avalanche, you are a long way from help in every direction. Skiers should be well prepared to self rescue in the event of an incident.