You can get to Kigali, Rwanda from Mwanza (departing at 5:30AM), from Arusha (departing at 4:00AM; transfers in Singida) or Dar es Salaam (departing at 4:00AM). I personally took the bus from Mwanza and would suggest breaking up the journey here as it is a lovely lakeside town!
Even though you are going to Kigali, the bus ticket is actually to a Tanzanian border town called Benaco, where you will transfer to the Rusumo border.
The bus is scheduled to depart at 5:30AM but we left closer to 6:00. I arrived around 5:00AM to claim my spot at one of the windows but to my surprise, the guy in charge was actually enforcing seat numbers (usually it's just a free for all, but this dude ran a tight ship). In this case I was very happy I had gotten my ticket the day prior as they had automatically assigned me a window.
The first stop is the Kimanga ferry, where you will get off the bus to purchase a ticket (500tsh) and walk onto the ferry. I was again shocked at the efficiency as the bus drove straight on the ferry and we departed shortly after. I had to hustle to get on board so anyone taking their time would have been left behind. We had a while on the ferry to enjoy the sunrise but were ushered back onto the bus before we arrived so we could drive off immediately after docking.
That didn’t put a dent in our 9 hour bus journey though. Once over the lake, the bus drives continuously until Benaco. A few stops are made to pick up new passengers who stand in the aisle (hence why I wanted a window seat) but no stops are official rest breaks so prepare your bladder. Definitely pack food and water (I use the Platypus bottle), though you can buy drinks, peanuts, bread and fruit from the bus windows during the brief stops. You may also want to pack some baby wipes or cleansing wipes as you will get really dusty by the window. Hand sanitizer is also a must!
What to expect at Benaco
Once at the Benaco bus station you can use a toilet located at the back or grab food or drinks from the stalls. Then you need to transfer to the Rusumo border crossing, so take a shared taxi for 3000 tsh (the taxi is essentially a normal car packed to the brim with bodies). I shared one with a few mamas and their babies, so I was quickly handed a toddler to hold for the bumpy 15 min ride.
The border was a little confusing (though it could have been my sleep deprived brain) so here are all the details you need to know. The first building you will see is customs to enter Tanzania. I went in to get my exit stamp and was told that they will do it at the Rwanda customs across the Rusumo bridge (weird but true). You can either take a motor bike taxi across the Rusumo bridge or walk. I walked and it’s about 10 minutes downhill and then another 5 over the bridge until you see the Rwanda customs building.
You will first report to the Tanzania desk to ‘exit’, and they will send you to the Rwanda visa desk. The Rwanda desk will give you a piece of paper that says $100 USD (assuming you are getting the East African tourist visa) and then send you to the bank window. You pay cash, receive a slip and return to the Tanzania desk for your exit stamp (no idea why you have to go there twice, but I watched him give me the exit stamp the second time I was there). The guy who gave me the exit stamp was the same man to print my East African visa and put it in my passport (like I said, confusing and a lot of back and forth between desks in the same room).