Hi caroline,
A few places you can visit...
1. Matheran: local trains ply on the Mumbai(DADAR) - Karjat/ Khapoli (Via Neral) route frequently. You need to take a local train on the central line in Mumbai going to Karjat/ Khapoli and get off at Neral. From neral take the toy train to matheran.. there is a taxi stand nearby the neral railway station you can get a shared taxi/van from there to matheran (prepaid booth is also there).. You'll have to walk a lot to see this place around.. lots of directions are placed inside matheran so finding your way will be easy.. Take the toy tain at east once - u can also book it in advance, please do that cause the rush is enormous for the train.
Nothing more than a broad hill top with lots of trees.. You also get various flavors of Chikki, local honey, fudge's (Chocolate and fruit flavours etc.).
2. Bordi: Nearest railhead is Dhanu Road, which is just 3 km away from Bordi town. Auto rickshaw is the cheap travel available, with a fare of less than Rs 20. for Dhanu road take a western line train.. its beyond virar so u might can take a long distance train.. cause most locals would terminate at virar..
The beauty of the place lies in the quiet sea beach, and the surrounding chikoo orchards. It also happens to be a safe beach, where the water does not rise above the waist for at least half a kilometre. The water however is black due to the dark sand and a little polution.
3. Borivalli national park: take a train to borivalli -western line.. From borivalli get an auto it'll take around 20 Rs to leave u at the national park.. Nothing worth seeing in wildlife.. you may take a toy train ride encompassing the park and then move to kahana caves - a nice unexplored trekking spot.. you can get a mini bus to the foot of the caves from the gate of the park.. remember the park closes at 6 in the evening..
4. Kashid & Murud: Wonderful beaches.. From alibag take a bus/auto to kashid. Stay there till evening.. Do not stay late as there is nothing even close to the beach. by sunset (probly before) move to murud.. you may find a bus plying to murud from the road adjoining the beach.. though it may take sometime before it comes along.. In murud u can look for a place to stay in one of the houses of the people living along the beach.. Its cheap.. breakfast/lunch/dinner can be found in one of the restaurants adjoining the beach.. a night walk on the beach is refreshing.. and the morning swim is awesome.. To goto murud janjira - morning is actually the best time... around 8 - 8:30.. take an auto to the ferry junction and from there u'll get a boat to goto the island castle.
5. Alibaug : Alibaug is easy to get to in about 2 hours by the combination of a catamaran/ferry from Gateway of India (1.5 hours) and then by bus from Mandwa jetty to alibaug (30 mins).
Kolaba fort: A prime location, this fort is situated in the sea at a distance of 1-2 km from the Alibaug shores. One can walk to the fort in at the time of low tide. Do not stay too long as u might not be able to return if high tide hits..
Akshi Beach: It is situated 5 km away from Alibaug nice beach.
Kihim Beach: Kihim is a private place at a distance of 12 km from Alibaug. The place is famous for intense cover of Coconut trees and forests which house butterflies, birds and flowers.
Mandawa: The catamaran/ferry services are available from Mumbai to the Mandawa jetty and back. this is were u'll alight from the ferry. U can have some fun with the speed boats here..
Nagaon beach: Located about 7 km away from Alibaug, this place is famous for coconuts. Nice beach to play around in..
Most places in alibaug are one way travel destinations. while you can easily find transport to them returning will require u to walk to a main road or prime junction before u can get any transport.
remember, if you are returning from alibaug, better book a catmaran early and be at the bus stand in time to catch the bus to mandwa.
6. Mahabaleshwar: Mumbai to Mahabaleshwar via Mahad is 220 kms, take an overnight bus to reach mahabaleshwar early next morning. you can get freshened up quickly at sulabh complex near the bus stand, or take a hotel.
Mahabaleshwa is best travelled on a cycle. you get cycles on rent at very low prices from the market. Have breakfast before you go looking for them as most cycle shops dont open till 9. There is also a bakery in the market wth lots of cycles parked in front of it. If u happen not to find one in the market this is a sure shot way to get it.. Just ask the bakery owner for the number of the guy who owns the cycles.. Mind the breaks and air pressure in the tyres.. very important..
TAKE CARE