Problems in the Hạ Long Bay
Fuel and oil, along with tourist litter, have created pollution problems, which impact on both the aquatic and terrestrial ecosystem of the islands. Human waste from portable toilets erected for tourists, finds its way into the soil and water surrounding the islands, once more altering the ecosystem functioning through increased nutrient flow.
The delicate limestone cave ecosystems are diminishing as tourists visiting the caves break off stalagmites and stalactites. Litter, including wine bottles, is dropped into cave streams and visitors exhale carbon dioxide, which has a deleterious affect on the caves. The mouths of some caves have been widened to allow tourist access. This increase in light has lead to an imbalance in the delicate links between the flora and fauna, and a decrease in the humidity of the caves.