Sondai Fort is near Karjat and very easily accessible from Mumbai. It is an easy track which can be completed in 1 hr time. The best time to track is in the Monsoon season as everything around you is lush green. You can also get alone kids 10 yrs and above and they will have super fun.

I you are living in south Mumbai we suggest you leave by 5:30 am and reach the base of the mountain by 7 am. As on weekends, there are too many people coming for the climb. You will find a long queue to climb the hill if you are late and that is no fun. Following is a google map link where you have to reach and start the climb: https://www.google.com/maps?q=18.94719123840332,73.29181671142578&z=17&hl=en

You can park your car at this destination.

Things to bring along with yourself. 1-liter water bottle, health snacks (Nutri bar, etc), One pair of clothes to change after the climb (you can keep clothes in the car).

You can easily reach the summit by 8:30 am and enjoy the breathtaking view. I assure you it is totally worth it. You can start climbing done at 9:15 am and can reach back to your car at 10:15 am. In monsoon, there is a waterfall nearby which is just 10 mins walk ahead from where you will park your car. Make sure you don't park inside the muddy area as chances are your car might get stuck.

You can reach back home easily before 2 pm. Hence this is a good and easily accessible track from Mumbai.

I suggest going along with your friends and family and enjoy nature this Monsoon. Enjoy :).