Gasherbrum II is situated in a very remote part of the Karakoram mountains. There are mainly two ways to reach BC.
Travel on rough roads from Skardu to Askole (6-8h).
Trekking Askole - Jhula - Paiju - Urdukas - Goro II - Concordia - BC takes anywhere between 3 and 8 days.
Travel on good asphalt (70% of the way) and rough track to Hushe by jeep (5-7h).
Walk Hushe - Gondogoro Pass (5600m) - Ali Camp - BC. 2 to 5 days.
Base Camp to Camp I
The route is different every year as you have to negotiate an icefall. It's is not a fast and unstable one as for ex. Khumbu or Mizhirgi, so the risk collapsing seracs are minimal under normal circumstances. Most climbers choose to go at night anyway as the snow holds your weight better and the negotiating of the crevasses are much safer. A huge majority rope up all the way from BC to CI, but early in the season and early in the morning the icefall can be travelled unroped without too much risk if there is no other choice.
A general description of the icefall
The flat part of the glacier.
The first part is quite flat, with smooth ups and downs. There are very few crevasses in this section and going is easy. Late in the season you may encounter quite big glacier streams and even small lakes appears.
The serac part.
Leaving the flat part, all of a sudden there are lots of seracs around you. The first climbers of the year have to find a way through this maze, but when a route is found, it's usually marked with flags and route finding is not hard. There are sections where you have to climb seracs, so crampons are needed in this part. There are very few crevasses in this section proper. In the end, when the icefall is flattening out again it's time to be very careful. Some of the icefall's most nasty crevasses are found here and some of them are of the more hard-to-see sort.
After you've passed the section with scary crevasses, you're all of a sudden "out in the open". A completely flat snow field has to be crossed. Excellent views of for ex. Gasherbrum IV in front of you. On this snow field some of the glaciers largest crevasses are located. They are usually marked, but pay extreme attention when in the sections where there are crevasses. Some may be unmarked!
The up and down part.
After the plateau you start to gain some altitude again. Some parts are steepish and sometimes it's almost flat. You walk through an undulating landscape of snow-walls, seracs and flat snow fields. This is an easy, but long section. Some crevasses here, but most of them are very easy to spot.
Pass some hundred meters from the base of Gasherbrum V and head for Gasherbrum II. You can't see CI until you're there, as it's hidden below a ridge on the huge snow field plateau.
To reach CI takes anything from three to ten hours, depending on load, acclimatization, snow conditions etc. Normal travel time is probably about five hours.
Camp I to Camp II
Walk the flat km from CI to the foot of the SW spur/rigde. No crevasses. Most climbers don't rope up or put on crampons until the climb proper starts. The ridge has broken up the last couple of years and nowadays the ridge is climbed from the west side, straight up from the snowfield, rather than the much smoother 35 degree walk which was the case before. Pass the first couple of rocks on the western ridge-face and look for a snow and ice passage close to them. Avoid to climb too close to the huge rock pillar on your left, as there are frequent rock falls there when the sun warms up.
The altitude gain is roughly 250 m to a little platform called "The Balcony". Average 50 degrees. Some sections with 60+ degrees in the end. Camping possible on the balcony. A popular rest and stash place, about half way from CII. May not be there next year.
Leaving The Balcony, you enter a long and exposed snow ridge. It's a 50 degree climb and even if exposed, very straight forward. The last part of this ridge is the steepest. You gain about 250m of altitude on this section.
The last part of the way to Camp II is a combination of traverses on snow, flat walking and some short sections of climbing. The first traverse is very exposed and steep.
Camp II is to be found on a platform and it's ok out of a safety angle. If there are extreme amounts of snow, watch out for avalanches. No big risk for a large one hitting the camp, but when I was there small powder snow avalanches went throught the camp.
Climbing times: I climbed to the balcony in 1h 45min and from there to Camp II in 1h 30min. No clue what's normal here.
Camp II to Camp III
This is also a part that probably changes a bit from year to year. The basic idea is the same though: to gain access to the ridge which leads to the flatter areas below the summit pyramid. In 2005 it was as follows. Some short, steepish sections had to be climbed directly after leaving Camp II. A flatter part took you to a snow wall with the face facing the SE. most of it was 55-60 degrees. When on top of this face, you had a huge drop to your left and had to change direction climbing the next slightly less steep snow-wall on your right. On top of this one it flattened out a bit and you had to aim at the steep serac wall. It could be climbed without too much hassle as the snow-ice mix was really good. Camp III is to be found on top of this serac wall. It's quite exposed to winds, but safe in terms of avalanches.
You can climb this section in less than two hours.
Camp III to Camp IV
The ridge leading to Camp IV is a mixed climb of snow and rocks. You better avoid the rocks as much as possible as the snow under normal conditions is a much better alternative. There are plenty of old ropes along the route and be careful which you use. Some have probably been hanging there since the beginning of Gasherbrum's climbing history. The mid section is the steepest, but it's seldom over 50 degrees. When the rocks starts to disappear, it also flattens out and you're getting close to Camp IV. It's very easy to find as there are dozens of "ghost tents" marking the spot. If you're in trouble and didn't bring a bivi-bag, you will find old tent-fabric en masse here. Another very safe, but exposed camp, which a lot of climbers bypass on the way towards the summit. Some pitch a tent here on the way from Camp III and use on the way down.
This part can be climbed in 2 hours, but I heard 3-5 is more common
Camp IV - Summit
The long traverse under the pyramid can be very hard if there are fresh snow. If there's a lot of it, this part is extremely prone to avalanches. In 2005 there were two alternatives - to climb close to the pyramid or below the huge crevasse lower on the traverse field. The crevasse was a "blind", so even if swept into it by an avalanche, you wouldn't fall to far. It may even save you from being swept over the brink an down the face itself.
After the long and sometimes frustrating (not much altitude gain) traverse, the route starts to go off more and more to the left and it gets steeper. Aim for the lowest part of the rock ridge. When at the foot of it and you round the corner, you probably think: Ok! It's not worse than that! It's refreshing to see the quite gentle slopes leading to the summit pyramid. About 40 degrees most of the way. The last part is on a ridge which is very airy. It is a very good idea to rope up the last part as a drop will keep you falling for almost 3000m. The summit was in 2005 covered by a corniche.
NB. There is one part on the final stretch which should be avoided. At one point, the obvious choice seems to be to your right, slightly down from the ridge. It'll take you to an unstable (looks very unstable) serac. Aim up the ridge, on slightly steeper than normal ground.
The difficulty of the route
The so called Banana Ridge have crumbled over the last couple of years. This has made "one of the three easy 8000'rs" much more difficult. Pakistani mountain guides told me the climb was very straight forward some years back, but nowadays it was a different story. What was a 35 degree walk on the first part of the ridge is now a 60 degree climb.
Three statements I heard during the climb of Gasherbrum II.
I don't like tech-climbing. I wish I was back on Everest.
Estonian Everest climber.
Manaslu was a breeze compared to this
Australian Manaslu summiteer.
For sure it's not like Broad Peak. That is a steep, but straight forward climb.
Italian climber who summited BP and G II.
That said, it's not a very technical climb in any way, but I met lots of climbers which thought it was a walk up like Cho Oyu, Muztagh Ata or even Elbrus.
The whole kit of gear that you need for an 8000 meter peak.
In terms of technical gear, not much is needed.
One ice ax, crampons, two-three karabiners, a jumar, walking sticks, prusiks, a rope.
If you happen to be first en route, you either have to bring lots of rope, ice screws, snow stakes etc. or you climb the route without fixed ropes. You can definitaly solo it or climb it on running belays.