Filfil sits on the slopes of the Eritrean Highlands where clouds roll in from the Red Sea and drop their moisture, keeping the forest wet and green all year. The canopy - the top layer of the forest - can be 20 or 30 metres high, and below it grow ferns, mosses and hundreds of plant species that depend on the shade and dampness.
The forest is home to olive baboons, green monkeys, bushbuck antelope and leopards. Many bird species live here too, including the African fish eagle, hornbills and sunbirds that flash like tiny jewels between the branches. Researchers still sometimes find species here that are new to science.
Filfil is important not just for its wildlife but also for the people who live nearby. The forest helps to regulate the local water supply - trees absorb rain and release it slowly into streams, keeping rivers flowing even in dry months. Villages downstream depend on this steady supply of clean water.
The Eritrean government has set up Filfil Solomuna as a protected national park, and rangers work there to look after the trees and animals. Visitors can walk on forest trails and spot wildlife from guided platforms, learning how a healthy rainforest works as a whole system where every plant and animal plays a part.