Cheap-ish outdoors holidays in Germany/ Austria

[Currywurst1]

Looking for a reasonably cheap outdoorsy holiday in Germany or Austria for me and my 6 year old.

At the moment not too bothered about specific activities, just looking to get a general idea of what is available and which areas are the cheapest. Could be in the forest, the mountain, lakeside etc. Activities that Interest us could be hiking, cycling, watersports, helping out on a farm, visiting a nature reserve etc. Mainly looking for something not in a city and where we can spend a lot of time outdoors.

I am aware of Bodensee, Obersdorf, Mittenwald and the lakes south of Munich but I am assuming that these may be the more expensive areas to visit. Sächsische Schweiz and the Seenplatte in Mecklenburg also appeal and may be the cheaper options but I am unsure of specific areas to visit and unsure how accesible these areas are.
Ideally looking for things that are doable with public transport as I would prefer not to rent a car.

Anyone have any tips?

Flights aren't bad to Munich and Nuremberg over the summer but nothing is really cheap in Germany unfortunately.
Try Airbnb, public transport is pretty good so you could try going just outside Munich somewhere near a tram or train stop, buses are ok as well but may not go very close to the swimming spots

Many of the ski areas operate summer passes which allow free or discounted use of ski lifts, swimming pools, mini golf and various other attractions when booked through partner accommodation. I know Zell am See in Austria does, as does Morzine if you'd consider France.

Have a look at Lipno in the Czech Republic, very beautiful and much cheaper than Germany/Austria.
Its a popular ski resort in the winter and a summer retreat with lakes, walks and loads of things to do.
Heres a link to the Trip Advisor page.

https://www.tripadvisor.co.uk/Tourism-g1056626-Lipno_nad_Vltavou_South_Bohemian_Region_Bohemia-Vacations.html

Eurocamp sites might be worth a look.

I know you said you prefer not to hire a car, but we got cheap flights to Munich and then hired a car last august and it was a lot cheaper than I thought. I think we paid £350 for 10 days hire and £80 return flights. We did a lot of day trips and stayed in the cheapest hotels, and brought packed lunches out every day so it worked out reasonable. We went to chiemsee, fussen, mittenwald, Oberammergau, neuschwenstein castle, tegernsee, eagles nest, konigsee, berchetesgarten (apologies for incorrect spellings, just off top of my head so haven't checked!) would recommend all of those. So sorry not what you asked re public transport but we initially planned to use the trains until we realised how reasonable the car hire from the airport was. I think they were called ok drive or something and I booked via rentalcars.com

I didn't know about the ski resorts so I will look in to that.
Eurocamp is also a good idea. We are not tent people but staying in a static caravan would be okay. I am more of a fan of self catering options so that could be a very good idea if I can find a place that we can get to without a car. I had an idea that these places were usually for people with cars but I will check it out.

Ski resorts have really invested in summer activities over the last few years - after all, the infrastructure and accommodation is already there. As the ski seasons are getting shorter, the summer season is becoming increasingly important.

Many Austrian resorts include a "Summer Card" - e.g. the Zell am See Summer Card mention above, or the Joker Card in Saalbach-Hinterglemm. Look at the Tourist Office websites for an overview of what's available and for some accommodation options. There are self-catering apartments (also sometimes on farms) as well as B&Bs and hotels. Campsites with cabins as well as tent spaces are also available. Whatever you choose, make sure that the accommodation provider offers the free tourist card - it is worth several hundred Euros in savings over a week for an average family. (There are a few threads already on MN about holidays in the mountains - in Austria, France and Italy - e.g. Page 4 | Alps summer holidays with two young boys! | Mumsnet).

Regarding public transport, there is a proposal to make all public transport in Salzburgerland free of charge for tourists over the summer - so for example, you could fly to Salzburg and then take the train or Postbus to Zell am See or Saalbach free of charge, and likewise explore the surrounding areas.

Hostels are worth a look. We’re staying in the one in Friedrichshafen next summer. You won’t need a car there either.

Friedrichshafen is a good shout.
I have eliminated Sächsische Schweiz from the list as it is not particularly easily accessible for me and fear that Mecklenburg will go the same way.
I think I will be looking at options in Bayern and NRW which seem to have better connected airports.

Any suggestions for the black forest would also be welcome if anyone has been there.

I seem to remember South Tirol being not too long a train ride from Verona so will also be widening my search to include that area too of anyone has any tips for child friendly activities and hiking routes in the region.

Have a look at Seefeld or the Zillertal valley. You can get to both areas easily on the train from Munich or Innsbruck
You can get a card in Zillertal to cover the gondolas/outdoor swimming pools/transport.

We have stayed on this farm before https://www.holtgraewe.de/index.html
A bit in the middle of nowhere, not your typical holiday destination, but plenty of things to do. The area is very flat and you can rent bikes.
To be honest, you can have a fab holiday anywhere in Germany. Easy to get to and a little off the beaten path would be the area around Frankfurt, the Rhön mountains (fly to Düsseldorf or Cologne), Lüneburger Heide (fly to Hamburg or Hannover), the Harz mountains or Weserbergland (fly to Hannover).

Very different neck of the woods, Baden in the South and close to the Black Forest, we have stayed here and it was wonderful!
https://www.weingut-landerer.de/ferienwohnung

Maybe a town in the black forest like Freiburg or Baden-Baden?