rwanda & tanzania: gorillas and mnemba island

Allow the better part of a day.

Our page fixes only the last stage: 90 minutes by road across Unguja from Stone Town, then a 20-minute boat crossing, and you wade the final few steps ashore, so pack shoes that come off easily and something dry for a camera.

The flights that carry you from Rwanda to Zanzibar are not written into the route and they turn on your dates, so we pin them down as we build the plan and leave enough room that a late arrival does not cost you the boat.

Light aircraft in this part of the world usually hold luggage to 15 kilograms each in soft bags, and what you carry on counts towards it. If the timings look tight, we add a night on Zanzibar first.

The route is built that way on purpose.

The trek is the fixed point, because a permit is issued for a named day and only eight exist for each gorilla family, so the forest sets your dates and the island fits around them. Putting the demanding days first also makes the five nights at the end proper rest, not a beach stay spent watching the clock for a 5am start.

The trek is a real climb at altitude as well, so this order gives you a night or two to arrive and settle before you walk.

We can turn it round if your flights home suit that better, and we sometimes do, though it leaves a long transfer and an early morning at the end of the holiday.

One hour, eight visitors and a mask.

Rwanda issues eight permits for each habituated family a day, the clock starts when the trackers find them and runs for sixty minutes, and masks are worn while you are close, because gorillas catch what we catch.

The rules ask you to stay about seven metres back, and the conservation group that trains the trackers asks for ten; the gorillas have read neither and may close the gap themselves, in which case do exactly what your ranger says.

Anyone turning up with a cold, flu or a stomach bug can be refused at the briefing, which seems hard until you remember how few of these animals are left. If a family cannot be reached at all, the booking rules provide for another attempt or a part refund.

The tides matter less here than on the long east-coast beaches, but they still set the rhythm.

Zanzibar's tides come twice a day and the range is wide, around a metre at neaps and over three metres at springs, so shallow water withdraws a long way at the lowest of them.

Mnemba is a small island inside its own reef, and you can snorkel straight off the beach as well as by boat, with reef walks going out at low water.

High tides fall about 12 hours and 25 minutes apart and slip roughly 50 minutes later each day, so whatever the water is doing when you arrive, it will be doing something else by the end of five nights. Dive sites are a short boat ride away.

There is a fair chance, and it is one of the few things on this trip with a season.

Green turtles nest on Mnemba, and their nests have been protected, recorded and tagged there since 1996. The main green turtle nesting season in Tanzania runs between February and July, with very few nests laid from September to December.

Eggs take roughly two months to hatch, so hatchlings can emerge at almost any point in the year. Seeing them means following the tracks up the beach and, with luck, watching hatchlings make for the sea.

None of it can be timed or booked in advance, and nobody can promise you a turtle on the sand. The team there will tell you what is happening while you are on the island.

June to September works for both halves: firm trails on the volcanoes, and the cool, settled months on the water when visibility is at its clearest.

February rates highly at both ends as well, warm and settled on the reef and dry in the forest. October still suits the island as Rwanda turns wetter, and January is the reverse of that.

April and May largely decide themselves, since the long rains fall in both countries and the island has an annual closure from 8 April to 20 May, which leaves only the first week of April and the tail of May open at that end of the year. March and November are wet on the volcanoes.

Tracking runs on all 365 days, so a wet month changes the going underfoot and not your chances, and permits come more easily then.