THANA-MUMBRA BY PASS-TALOJA-PANVEL-PEN(on GOA road)-wadkhal naka(don't turn left on cos it goes to goa) keep going straight- in the hils there will be a right(don't take it) continue straight you'll pass a dam wall continue straight and soon you'll be in alibag.
alternate from thana-aeroli-sanpada-belapur-panvel- then its the same.
From Panvel its 35 kms to Wadkhal naka where you'll pass the market place and you have to continue straight to alibag.