Masasi is a town in the South East region of Tanzania.
Buses to Dar es Salaam (9+ hours) depart early in the morning. Get a seat near the front as part of the road is unpaved.
For transport heading further inland ask around at the bus stand. Towards Tunduru there is a new modern road as far as the village of Mangaka but the next section is not yet paved and is very unpleasant in the main wet season. If you want to see the Unity Bridge which goes over the Ruvuma River to Mozambique there is a well made murram road towards the bridge from Mangaka.
MAF operate a small plane which goes to Masasi on demand on Thursday as part of the "Southern Shuttle". I've used it to fly from Dar es Salaam. Email; firstname.lastname@example.org Website; http://www.maf.or.tz It's a long walk from the airfield to town but you are likely to be able to find a lifti.
According to some guide books there is a rock art site within walking distance of Masasi although I am yet to meet anyone who has found it. There's a great panorama to be seen from the top of a big rock next to Mkomaindo Hospital, Just West of the town by the new road to Tunduru. Drive towards the Unity Bridge over the Ruvuma River and you might see some of the numerous elephants in the Lukwika Lumesule Game Reserve, though not in the dry season.
There are a few small hills around Masasi and it is possible to hike up them.
There's a food market and plenty of shops. A bank just back from the main road has an ATM for debit cards like VISA. Just out of town on the road to Nachingwea there's a Makonde carvers group with plenty of ujamaa and other carvings.
Several bars are easy to find. For good atmosphere in the heat of the day try the cafe/bar with open-air shaded seating just back from the main road on a corner, south side.
There are no tourist guest houses but the town is a major center in the cashew nut trade so there are a large number of guest houses in the 4'000/- to 30'000/- range. You will get what you pay for. Just East of the town there's a good guest house by the Anglican Cathedral, right by the small mountain called Mtandi. Rooms are self-contained; meaning they have shower and toilet. Ask at the Diocese Office.