I recently took a quick trip up to Grindelwald and it was a magical winter paradise.
Grindelwald is a small mountain village nestled in the Bernese Alps. The Grindelwald and Lauterbrunnen valleys split off from each other near the city of Interlaken, which is considered the gateway to the Alps.
If you are in Switzerland and want to visit Grindelwald by public transportation, you would take a train to Interlaken Ost (the east station in Interlaken). Interlaken has two stations, Ost and West. They're maybe a 20 minute walk from each other but Ost is the larger of the two and where the trains to the alps and international destinations depart frohm. Once in Interlaken, there is a train that goes into the main valley and splits off. Half of the train continues to Lauterbrunnen and half goes to Grindelwald. When you board the train, make sure you are on the appropriate section. There are signs on the ground directing you where to go and the train cars tell you which destination your particular car is heading to. The train attendants are also very helpful and will point you in the right direction.
The train ride from Interlaken to Grindelwald is lovely, with gorgeous views of the forest and eventually the village. In winter there is winter hiking, snowshoeing, sledding, and of course skiing and snowboarding. It's a winter wonderland!