From AllTrails:
The start of this tour is at the Schynige Platte. The train that takes you up comes from the 19th century and is reminiscent of the times gone by. The path then goes to the Bachalpsee, also called Bachsee. It is located at 2265m above sea level.
Updated: This is a point to point trail. If you are able to hike fast enough and start early enough, the hike can be done as an out and back from Schynige Platte just to Bachalpsee. Another option (as shown here) is to hike from Schynige Platte to Bachalpsee and finish in Grindelwald First then take the Gondala down from there.