“Some of the awesome beaches for overnight picnic and camping in and near Mumbai for beach side night camping under stars and moonlight. Those beaches are not far from Mumbai, ideal for an overnight spent as group picnic and not recommended for individual couples..”

Arnala beach : Located at Virar, far north location at about 60 to 70 Kilometres from Mumbai on western railway route, Arnala beach is already a very famous tourist destination for a picnic and resorts around.
3 connected beaches makes the coastal very long and all these beach fronts are awesome at nights. Immediately connected is Navapur beach (Video Below) which also has couple of resorts near beach, then there is Rajodi and Kalamb beach straight in line with nearest station Nalasopara which is next station to Virar. More ahead 3rd station Vasai is Bhuigaon beach.
All the above listed beaches are bit isolated with villages around and that’s the reason i recommend to do your overnight camping on these beaches in group and not as couple.
At times during Amavasya sky are very dark and sometimes with ample moonlight it looks blue with glittering stars. The serenity with the only sound of white looking waves will drive you romantic and will take few to the dream world and is the reason why i listed these beaches for overnight picnic.
Going little far ahead of Virar at another 1 hour road journey is another clean beach called Dahanu Bordi Beach. This beach is about 140 Kilometres from Mumbai city and a very ideal camping locations to spend night over some fun with picnic group. Its a single wide beach, clean enough with glowing sea water during full moon night.
On western suburb towards Mumbai is a railway station called Borivali which has a famous beach called Gorai and an adjacent beach called Uttan beach which can be reached from Bhayander station.
Head South Mumbai and get a ferry to Alibaug which is a famous destination and has couple of serene beaches for overnight picnic. It is already a famous destinations for day picnic.
To help you travel here are railway station names of Mumbai to better understand locations of each beach.
Note : Almost all beaches listed for overnight picnic and camping fun near Mumbai have resorts around. You might also like to read about all picnic spots in and around city.