We put our first cache here to People's Island. My wife lived nearby so she walked here a lot. From the nearby school they often brought the kids to play here. Most of the island is flood area, but I think I could find a place, where the cache is in a safe place. Next to the cache you could meet a lot of people with dogs. Basically there is a dog school.
To approach, go to the "Újpest-Városkapu" stop with Metro line 3. Here you can park with your car too.
The cache is preserving jar. I tried to hide well. I'm curious about how you like it! :))