As the weather forecast is looking good for Wednesday we shall be going to Pfaueninsel.
The day-trip operates on a pay-your-own-way system, basically buy your own tickets for things.
You will need a normal Berlin AB travel ticket for this journey. Take S7 to Wansee S-Bahn station (nearest station to TU is Zoologischer Garten), from the platform go down the steps, turn right and go to the end of the tunnel and up the stairs. Continue to the bus stop just after the shelter, we are getting bus 218 to Pfaueninsel. The buses are only once an hour at 13:51,14:51 etc lasting 10 minutes. It is the last stop on the bus that we get off, this will be where the majority of other people get off as well. It is then a short ferry journey over to the Island (4€ return, pay as you get on the ferry. there is no further charge for the island).
There will be a group leaving from TU at 12:50 to get the U2 from Ernst-Reuter-Platz to Zoologischer Garten, then the S7 leaving at 13:22.
We will spend the afternoon there. Where you can wander about exploring the island and chatting to other people in KDE. Near the middle of the island there is a place to buy drinks and snacks. The palace tour is only available in German and for most people probably not that interesting. The island "closes" at 19:00.
On the mainland at the ferry crossing is Wirtshaus zur Pfaueninsel however the last bus back to Wansee is at 20:04 so it is recommended to go back into the centre of Wansee to get food and drinks where there is Loretta am Wannsee next to the station. There are also some shops at the station where you could buy food and drink to take down to the seating at the edge of the river at Ronnebypromenade.
Some people may wish to stop off at Grunewald S-Bahn station to visit the Gleis 17 memorial, you can then just get on the next train to continue to Wansee. If you are interested in doing this there will be a group leaving slightly earlier from TU at 12:20.