Swan Lake Park is located in the location of "Boston Park", which is not marked on the map (sending it to Boston Park is equivalent to sending it to the vicinity of Swan Lake Park. In two overlapping places, B Club is too lazy to make detailed delivery points, such as the Sorgus blast furnace in the Sorgus ironing workshop).
How to find Boston Park:
There is a barrier-free subway station "Park Street Station" near Boston Park. There is an abandoned shelter (No.1 14 shelter) hidden under this station. 1 14 shelter is also where the bandit leader "skinny Malone" holds Nick Valentine, so when you find Park Street Station, you will find it, too.