As Mpulungu is the end of the route, most of the buses from Mbala tend to arrive in the afternoon and evening, and those departing tend to leave in the morning. The 'terminus' is on the main road, beside the market area – you cannot fail to go through it.
Hitching here from Mbala in the afternoon is very easy, with lots of lifts. However, getting out again in the morning is virtually impossible. Everybody who has a little space in their vehicle goes to the area for buses and fills up with paying passengers, so few are at all interested in a stray hitchhiker walking away from the main station. So, if you want to get out of here then go with the crowd and hang around the main market area quizzing any likely buses or vehicles. Because of the steep, twisting road out of the valley, heavy or under-powered vehicles can be painfully slow, so get a lighter, more powerful lift if you can.
There are two large international Tanganyika ferries each of which calls at Mpulungu once every week. Both arrive in the morning and leave in the afternoon: the Liemba on Fridays and the Mongosa on Mondays.
From Mpulungu they sail over the Tanzanian border to Kasanga, then to Kigoma in the north of Tanzania, and then on to Burundi. (This last stop is sometimes omitted due to the dangerous security situation there.) The ferries stop at countless places in between these more major ports.
The Mongosa was out of the water and allegedly undergoing repairs since 1999, but there's no sign of it returning yet. This leaves just the Liemba as a once-weekly service on a Friday. First class is comfortable with videos for entertainment and meals of rice and fish or chicken, while second class is considerably more basic.
If you need a short trip out to one of the lodges on the lake then hire a boat-taxi from the beach-side market, next to Andreas Fisheries Ltd. You will need to make sure that the driver knows the lodge that you want, and exactly where it is, and you may want to bargain over the rate a little.
It's essential that you have a crystal-clear deal over the price for the trip, including you and all your baggage, before you set off from Mpulungu – as disagreements on arrival (or worse still, on the lake) are bad news for you and the person running the boat.