Transfer from Lucerne to Grindelwald
Today you have the option between a fast and a scenic train. The fast train goes via Berne to Interlaken while the scenic train goes along lakes and over a mountain pass! It is the route I told you about which also allows for a partial lake adventure!
Train Only:
You have a direct train at :05 minutes of every hour leaving from track 12. This train is the scenic train "Golden Pass", but also has regular 2nd class wagons which do not require a seat reservation. The train takes 1 hour 50 minutes to arrive in Interlaken East.
If you do make today a full day with trains, boats, and possibly visiting Interlaken, then you might want to use the Fast Baggage described in the beginning. I am giving you the "maximum" version here, and then you can decide what you prefer. In general the boat and train schedules are synchronized, so you never have to wait long...
Maximum version:
1- Boat from Lucerne to Alpnachstad (Lake Lucerne) at :38 of every hour, 1st at 8:38 AM
2- Train from Alpnachstad to Brienz at :59 of every hour
3- Boat from Brienz to Interlaken East (Lake Brienz) at :40 of every hour*
*the train at 12:40 PM and 3:40 PM are supposedly served by a historic lake steamer.
Brienz is a wood carving village on the lake shores, and also make for an excellent stop to have lunch.
Interlaken East to Grindelwald:
In the afternoon you have always two trains per hour, leaving at :05 and :35 of every hour and taking approx. 35 minutes. The trains will have separated in Zweilütschinen so make sure you sit in the half which goes to Grindelwald (not to Lauterbrunnen).
Both trains and boats are included in your Swiss Passes!