If you talk to someone who has been fortunate enough to visit the mountain gorillas of Rwanda and Uganda, you’ll be treated to an enthusiastic, if not rhapsodical, explainer on why the experience is both magical and moving.

To be sure, trekking through emerald rain forests searching for one of humankind’s closest relatives is nothing short of spectacular. It’s also rare.

Today, only about 1,000 mountain gorillas are left, making the species critically endangered. The sole way to see them (there are none in zoos) is by trekking in certain East African national parks (Volcanoes National Park in Rwanda, Virunga National Park in the Democratic Republic of Congo, and Bwindi Impenetrable National Park and Mgahinga Gorilla National Park in Uganda). That trek also needs to be with a certified guide for your protection and the protection of the gorillas. From costs and permits to tour providers who can organize it all, here is how to plan a gorilla trekking trip.

How much does it cost?

The price for a full tour, including permits, guides, lodging, and additional add-ons can vary wildly, but expect to spend per person around $1,000 on the low end and $15,000 on the high end for a gorilla trek. Prices can vary depending on if which country you’re trekking in—permits are $700 per person in Uganda but $1,500 per person in Rwanda—your accommodation type, the tour provider you select, and whether there are other excursions planned for the tour (like additional treks or safaris).

The permit price helps the countries with protection and conservation efforts—particularly important, considering the mountain gorillas are critically endangered. Generally speaking, 15 percent of the money collected from gorilla permits goes to the government, 10 percent to the local communities, and 75 percent to gorilla conservation.

Most operators include the price of the permit in the overall tour, but be sure to double-check with your company. At the very least, your tour should include lodging and meals.

What is likely not included is the tip for the guide and the porter (should you choose to use one). For guides, $25 per traveler is recommended. For porters (someone who carries your backpack and helps provide an extra hand when crossing trickier parts of the forest, like going up muddy hills or over large fallen trees), the going rate is a minimum of $15. Even if you’re fit and aren’t carrying much, most guiding companies recommend getting a porter. Although $15 may not seem like much to you, the sum is hugely important to them. It also helps the locals benefit from ecotourism, which in turn shows them the value of protecting the gorillas. Some of the porters are actually former poachers who have come to realize that there’s greater value in conservation.