Named after the Mahale Mountains range that is within its borders, the park has several unusual characteristics. First, it is one of only two protected areas for chimpanzees in the country. Another unusual feature of the park is that it is one of the very few in Africa that must be experienced by foot.
The park headquarter is located already inside the park at GPS: -6.035154, 29.741279.
Another official office of the park is located further north at the air strip at GPS: -6.011507, 29.764750.
The name "park entrance" is not clearly defined. It is often used ambiguously and is not very helpful since your final destination will be the place where you can actually sleep (or start the chimpanzee trekking if you are not planning on staying overnight; these are the same locations). This may be tricky when bargaining about boat prices with locals.
Take the park boat to the park entrance (USD200). The MV Liemba can radio them, so they can come and get you from Lagosa.
Take a local boat to the park entrance. Depends on your language and bargaining skills (DoyLaBs). Very tough to arrange. Only very few people in Lagosa speak English and they may not be there when you arrive at the beach or may not offer boating services.
Take a motor cycle from Lagosa to the Airstrip (about 30-40 Minutes and TZS15,000 per Person - DoyLaBs), where an official park office is located. They are able to arrange further transport.
Airstrip to Kasiha Bandas (about 19km by boat) will cost you TZS66,150. See calculation in [Get around].
They will also have you buy the ticket for the boat to take you back. The city closest (and therefore cheapest) to the northern boundary of the Mahale Mountains National Park is Kililani. From there you would need to figure out a way to get back to Lagosa to take the MV Liemba.
Official Park Boat In a brochure, they claim they can also pick you up in Kigoma with their boat. I have never heard about this while there and since the distance is about 180km the cost will be quite high and may be at around TZS800,000 (one way). This is an estimation based on the actual charges for shorter distances (see below). Check with the park official for the price. Depending on your group size and the capacity of the boat, this may still be reasonable to do. However, keep in mind that this will take a while and you will miss the experience of sailing with the MV Liemba.
Charter plane You can fly in with a private charter plane. Usually these flight are arranged as part of complete package with the stay in the park. The Nomad camp is offering this . Also the Mbali Mbali can arrange this . If you get lucky you can hitch a ride with a plane. It may get cheaper then, but will still be expensive. From the air strip take the official park boat.
Prices depend on fuel consumption and rather arbitrary calculations (see difference in km and difference in fuel below) by the park officials. They claim one liter fuel costs TZS3,150 and charge an additional 40% of the fuel price for wear and tear (Oct 2014). Examples of actual charged prices in Oct 2014:
Airstrip to Kasiha Bandas (about 19km): 25 liters (TZS47,250) + 40% Wear and Tear (TZS18,900) = TZS66,150
Kasiha Bandas to Kalilani (about 14.5km): 15 liters (TZS110,250) + 40% Wear and Tear (TZS31,500) = TZS110,250
Kasiha Bandas (GPS: -6.117289,29.730789) are self catering. A kitchen with basic equipment can be used. Bring your own food. USD40 per person per night will be charged when entering the park. Bandas have two Queen size bed and sleep two persons (or two couples?). They are very well kept and nice.
Other camps, including Mbali Mbali  (GPS: -6.129121, 29.731559) and Nomad  (GPS: -6.138535, 29.733037), are quite expensive and offer full board. If you can afford them, they are probably a very comfortable option.