The route to Diveagar from Mumbai is pretty much straight forward. To reach Diveagar from Mumbai one needs to follow the NH 17 till Mangaon, approximately 100 Kms from Panvel. A right turn from Mangaon leads to Diveagar via Mhasala.
Nearest railway station is in Mangaon. (Mangaon to Diveagar > 50 Kms)
There are three routes from Pune to reach Diveagar however considering the current road condition and distance the route via Bhor - Verandha ghat would be the best route to take. The Bhor - Verandha ghat meets the NH17 at Mahad. Take a left at Lonere which is about 20 Kms from Mahad. Diveagar is approximately 50 kms from Lonere via the Goregaon ghats.