Ratargul is a forest you explore by boat, gliding between the crowns of trees that stand drowned for months at a time. Each monsoon, from June to September, the Gowain River rises and floods the woodland until the trunks sit three to six metres underwater, their branches almost brushing the surface. The water comes off the hills of Meghalaya just across the Indian border, where some of the heaviest rain on Earth falls. This is a freshwater swamp forest, one of only a handful left in the world and the best known in Bangladesh, where people call it their Amazon. The koroch and hijol trees that make it up are built for the flooding, and their blossoms wash the canopy in colour. In the dry months the water drops and the bare roots stand exposed; only when the flood returns does Ratargul become the green labyrinth it is known for.
You go in by narrow wooden boat, and once the oar stops the forest falls almost silent — only birdsong, the hum of insects, and water sliding past the hull. Light comes through the leaves in shades of green, and the water lies so still that it reflects the canopy almost perfectly. Snakes rest on low branches, monitor lizards bask along the banks, and kingfishers, herons and winter migrants work the shallows; from a raised watchtower the trees spread into a green sea running to the horizon. Ratargul is fragile, though, and increasingly it shows: only a small core is strictly protected, and roads, fences and heavy tourist traffic pushed into that core have drawn protests and court petitions. Boats now enter only with permission from the forest office, because keeping visitor numbers and noise low is what gives the protected core a chance to recover.