Nepenthes rafflesiana is the most dramatic carnivorous plant at Bako National Park. Its upper pitchers — the elongated, tendril-suspended traps produced by mature climbing vines — can reach 35 cm in depth and hold over a litre of digestive fluid. Rat carcasses have been found inside the largest specimens; a pitcher of this size can digest a small vertebrate within days. The species was named after Sir Stamford Raffles, the British colonial administrator who commissioned early natural history surveys of the Malay Archipelago.

Unlike the ground-hugging rosettes of Nepenthes ampullaria, N. rafflesiana is a climber. Juvenile plants produce squat lower pitchers at ground level, but as the vine grows it produces upper pitchers that hang from tendrils in the mid-canopy. The two pitcher types look quite different: lower pitchers are wider and often heavily spotted, while upper pitchers are narrower, more tubular, and usually unspotted. Both use the same trapping mechanism — a waxy inner surface that insects cannot grip, plus downward-pointing hairs that guide them into the fluid below.

The pitchers are colonised by a diverse inquiline community. The mosquito Tripteroides tenax breeds only in N. rafflesiana pitchers. Several species of mite and a specialised ant, Camponotus schmitzi, are known to forage inside active pitchers — the ant is immune to the digestive enzymes and feeds on captured prey, which some researchers argue helps the plant by keeping the pitcher clean. A tree shrew (Tupaia montana) has been observed drinking nectar from the lid of large pitchers while simultaneously depositing droppings into the fluid — mutual feeding that provides the plant with nitrogen.

At Bako, look for mature climbing specimens along the forest edges on the Lintang Trail and the Bukit Gondol approach, where the vegetation transitions from beach scrub to taller forest. The large hanging upper pitchers are most visible in the first hour of morning light, when the fresh dew on the waxy rim glistens. The park's full carnivorous plant guide lists all five Nepenthes species recorded at Bako.