Here are few such destinations that are not as popular or rather less explored than the regular ones. Some of these destinations, you may find very near from you and can be ideal foil for one day or weekend outings.
Explore these places :
Amboli | Anjaneri | Anjanvel | Aronda | Battis Shirala | Baneshwar | Bhuleshwar | Bor Dam | Bordi | Dhutpapeshwar | Dive Agar | Durshet | GMRT Narayangaon | Igatpuri | Junnar Caves | Kanheri | Kaas Plateau | Keechakadara Hill Station | Kolad | Khodala | Kopeshwar | Lonar | Marleshwar | Narnala | Nawegaon Bandh | Palghar | Phansad | Pitalkhora | Ramdara | Revdanda | Redi | Sagareshwar | Siddhagiri Museum | Toranmal | Tulapur | Ujni | more to come..