The short version
Tanzania is large, and the map flatters it. Two parks that look adjacent can be most of a day apart by road. How your group moves between them is not a detail of the itinerary, it is one of the things that decides how much of the trip you spend actually looking at anything.
Light aircraft
Short hops on small aircraft link the main parks and the coast, and on a trip of ordinary length they frequently pay for themselves in recovered days. They come with the strict baggage limits covered in the packing list, they are weather dependent, and schedules can move. Build a little slack around them rather than connecting tightly to an international departure.
Road
Road transfers are how you see the country between the destinations, which is a real argument for them. They are also long. Surfaces vary considerably, journey times are governed by conditions rather than distance, and driving after dark is something a well run operation avoids.
For groups we use vetted operators and drivers rather than whoever is available, and we plan departure times around arriving in daylight. That constraint shapes the itinerary more than most travelers expect, and it is not negotiable in our planning.
Getting to Zanzibar
The island is reached by a short flight or by ferry from Dar es Salaam. Both are used routinely. The choice usually comes down to your group's tolerance for sea conditions and how the timing fits the rest of the day.
Remember that the eVisa covers both Tanzania Mainland and Zanzibar, so this is an internal movement rather than a new entry requirement. See the visa and entry requirements guide.
In the parks
Game viewing is done in the operator's vehicles, on the park authority's terms: TANAPA sets the rules on where vehicles may go, and off road driving is restricted. A guide who declines to leave the track is following the rules that keep the park worth visiting, not being unhelpful.
What we do
We plan the movement first and hang the itinerary on it, because transport is what turns a good list of places into a trip that works. For a group that includes a single point of contact when a flight moves, which is the part that matters at the time.
Planning with LABUSA Travel
We plan and manage Tanzania journeys for groups: itinerary design, park permits, lodges, internal flights and ground transport, and a single point of contact while you travel. Start with the Tanzania travel guide, or tell us what your group has in mind on the plan your trip form.