The park is very near Paris and is just a 10-15 minute walk from the metro station 'Marie de Montreuil', which is the last stop on line 9.
Outside the metro look for the obvious, big and imposing Soviet-style town hall. Walk away from it along Ave Walwein; on your right is a line of bus stops (with the new shopping-centre behind). At the crossroads (driving-school on corner) go straight on, and up a hill.
At the next crossroads, keep going straight on (road is now rue Galilee). At next crossroads (flower shops) go straight on, past the cemetery on your left, and down to the T-junction at the end of the road. Go right here, walk some 70M, and there is a Nature Reserve sign and steps leading up through woodland. Keep walking upwards and you will eventually find the pond (Mare Perchee) and the surrounding habitat which, compared to a Parisien park, is quite exciting-looking.