The Kanheri Caves situated amidst dense forest, are an ancient Buddhist site dating back to ~2BCE. Interesting at all times, they are magical during the monsoons when the surroundings are a lush, verdant green replete with waterfalls.
We went there twice recently within a span of 10 days. The first visit was during a bout of heavy rains and the caves had transformed into waterfall wonderland when the focus of the visit was the gushing water rather than the heritage. The second visit was dry but overcast, ideal for exploring the caves though a tad slippery!
The caves are situated within the Sanjay Gandhi National Park at Borivali East, about 4km from the main entrance to the park. One can walk or cycle the distance to the caves along the road through the forest, or drive (only private cars/bikes, private taxis are allowed - no autos, no black/yellow cabs) or take a shuttle bus (not on Thu). Note that the Park opens at 07:30 but the caves open only at 09:00.
Some of the caves have beautiful stone carvings - notably Cave 2, 3 with its big chaitya hall and two colossal Buddhas, 4, 41 with its unique eleven headed Avalokitesvara, 67 the Chitrashaala and more ... don't remember the numbers! Most though are austere cells, some are unfinished, some almost 'caving' in so to speak. Cave 34 still has remnants of painting on the ceiling though it is very dark. The necropolis is supposed to be Cave 89, we could not go there this time as it was far too slippery, better for a dry season visit. Overall, this is an exciting experience being a unique combination of a heritage site in the middle of a forest. Kanheri surely deserves a UNESCO Heritage tag and I hope it gets it one day.
The ASI who administers the caves, has a posse of security guards on duty these days. This is most reassuring as in the past there were several incidents of robbery at Kanheri especially in the more remote cave sites. Another plus point is that proper walkways have been made, making it easy to navigate the site. Previously it was rubble or narrow stone pathways. Some of the original steep stone stairs are still there, leading to the top of the basalt plateau with nice views of the forest, the city and Tulsi Lake.
I have been going to Kanheri for the past forty years or so and I highly recommend this visit. Food is available from a stall at the caves entrance and also from the stalls that the Adivasi forest dwellers put up along the roadside. Otherwise, pack your own picnic and enjoy! Weekends especially monsoon weekends are VERY crowded and highly avoidable if you want peace and quiet.