Coastal temperate rainforests, among Earth’s carbon richest biomes, are systematically underrepresented in the global network of critical zone observatories (CZOs). Introducing here a first CZO in the heart of the Patagonian rainforest, Chile, we investigate carbon sink functioning, biota-driven landscape evolution, fluxes of matter and energy, and disturbance regimes. We invite the community to join us in cross-disciplinary collaboration to advance science in this particular environment.