Day trips from Interlaken

In Interlaken, Harder Kulm is nice if you just have a couple of hours at the end of the day. A boat trip on Lake Brienz would also be very enjoyable, and you can make a full day out of it if you include the cog railway to the Brienzer Rothorn.

Further towards the Jungfrau, the easy hike from Männlichen to Kleine Scheidegg is highly recommended. Or you could head to Bachalpsee (and Faulhorn if you're fit with proper hiking shoes), up from Grindelwald.

If weather is not suitable for mountains and lakes, you could visit Bern.

All of this is very easy to do on your own.

You could train the train to Lauterbrunnen and walk to Staubback Falls. You can actually walk up to and go behind those falls. You could also go to trummelbach falls. You can walk or take the bus there.

As balso suggested, I would definitely go up to Wengen and then take the cable car to Männlichen. Even if you don’t want to walk down to Kleine Scheidegg, you can just walk around Männlichen a bit and take the cable car back down to Wengen.

Another option is a boat cruise on Lake Thun to see the 5 castles that are on the lake. From Interlaken, the boat will take you to Thun. You can walk around a bit, go see the great castle there, and then take the train back to Interlaken.

To reiterate what balso has said, Switzerland is very easy to get around. So, you can definitely do those things on your own. If you have a smart phone, you’ll want to download the SBB app and practice using that before you get to Switzerland.

Thank you both for your suggestions! it took me a while to research each of your ideas, but all look enjoyable :-) A few additional questions: for the Mannlichen to Kleine Scheidegg hike, it looks like i can take the train from Interlaken to Grindelwald then a cable car to Mannlichen , or, train from Interlaken to Wengen and then onto Manlichen. is one way better or easier or suggested?

For the Castles on Lake Thun, are all of the castles open to enter, is there a separate admission charge for each and can you walk from one to the other? or are they hotels or serve different purposes currently?

Also, do you need reservations for Harder Kulm? looks like it is currently not open yet for the season to check.

If we have a few hours left in a day, is there anything much to do in Interlaken? (shops, etc?)

No reservations for Harder Kulm, it is just a funicular railway on the edge of town. Quick visit.
And Männlichen is indeed significantly quicker to reach from Grindelwald Terminal than from Wengen.

Good to know to travel to Grindelwald terminal. that is what i was thinking as well.

I didnt realize Harder Kulm was a a funicular railway, when i googled it, i thought you were referring to eating dinner in the restaurant, however i assume i could do both while there? looks beautiful!

How about an electric bike ride or is that way to challenging for a basic rider looking to sightsee?

Regarding the Lake Thun castles, this website has all the info.

https://www.thunerseeschloesser.ch/de/

Click at the top on each castle to get the info. on getting there, opening hours, etc.

They are too far apart to walk and see them all. And the timing of the boats makes seeing multiple castle difficult as the boats don't fun that frequently.

We liked castle Thun the best. So, you could take the boat from Interlaken to Thun and then walk to see that castle. The other castles you will be able to see from the boat. You could take the train to the Spiez castle, but the train station is a bit of a walk to the castle. And it's uphill going from the castle back to the train station.

If you decide to take the boat around Lake Thun, it stops at Castle Oberhofen (admission required), and there is a nice park near there, which is free.

https://www.schlossoberhofen.ch/en/schlosspark/der-schlosspark

You can then take the boat to Thun in order to visit Thun Castle, or if you don’t want to wait for the boat, there are buses that depart near Castle Oberhofen to Thun. It’s about a 15 minute trip, and they run about every 15 minutes, and would drop you closer to Thun Castle.

Thun has some interesting architecture around the Aare River, especially in the Old Town at Obere Hauptgasse which has raised sidewalks. There are nice cafes along the river, and and a pleasant walk along the lakeshore at Schadau Park with great views of the Alps.

You can catch the boat from Thun to continue around the lake.

If you only have time for one castle, then I would stop in Thun for Thun Castle and explore the town a bit before resuming the boat trip. Of if you don’t want to ride completely around the lake, you can catch a bus back to Interlaken from Thun.

Also, from Interlaken it’s about a 30 minute bus ride to Beatenbucht at Lake Thun. From there you can take the funicular railway to Beatenberg Station, then take a cable car to Niederhorn (about 30 minutes total). Or you can take the bus to Beatenberg Station.

Niederhorn offers an impressive view of the lake and the Alps.

All the best,