Mounted on the upper deck of a passenger ferry, a dolphin statue frames the Port of Tanjung Perak in Surabaya, a coastal city on the Java Sea. The terminal is the secondLloyd's List – One Hundred Ports, 2025 busiest container port in Indonesia, and the primary logistic hub to connect the central part of the country’s vast archipelago to the eastern provinces. For decades, the port has functioned as a gateway to support Indonesia’s push to raze its primary tropical rainforest and convert it into economically productive land through agriculture and mining. Meanwhile, the maritime hub has contributed to funnel commodities extracted from deforested lands to global markets.

Beyond Indonesia, Tanjung Perak is a node in the global ocean freight network, in which about 40%United Nations Trade and Development – International maritime trade, 2022 of transported cargo consists of fossil fuels. This worldwide logistics web largely runs on heavy fuel oil, a viscous residue from crude oil refining processes that causes sulphur pollution, contributing to the acidification of oceans. The increase in acidity of ocean waters, estimated at 25%U.S. Environmental Protection Agency – Understanding the Science of Ocean and Coastal Acidification, 2026 in the last three centuries, affectsNatural History Museum – How does ocean acidification affect marine life the food chain marine mammals feed on. For example, pteropods, a component in the zooplankton diet of several whales, have been observed to slowly dissolve after 45U.S. National Oceanic and Atmospheric Administration – Ocean acidification, 2025 days in sea water with acidity levels projected for 2100.

In addition to disrupting food chains and leaching into the ocean chemicals, heavy metals, and plastic particles contained in hull coatings, shipping fleets routinely collide with marine mammals. Vessel strikes are estimated to kill between 18,000Friend of the Sea – Why are so many whales colliding with ships, 2022 and 25,000 whales each year, although reliable statistics are limited since many collisions go unnoticed or unrecorded. The probability that a strike will be fatal reaches 80%International Whaling Commission – An Assessment of Collisions Between Vessels and Cetaceans Using Available Data in the IWC Ship Strike Database, 2020 at 15 knots, roughly the average speedUnited Nations Trade and Development – Review of maritime transport, 2025 of container vessels plying shipping lanes. The strike risk is exacerbatedThe Animal Fund – Boat Collisions with Whales, 2023 by a human-made cacophony. Ship noise, known as underwater-radiated noiseInternational Maritime Organisation – Revised guidelines for the reduction of underwater radiated noise from shipping to address adverse impacts on marine life, 2024, causes an acoustic fog that interferes with the frequency range that marine mammals use to navigate. The threat is projected to intensify as more acidic ocean water carries sounds fartherMonterey Bay Aquarium Research Institute – Sounds Travel Farther Underwater As World's Oceans Become More Acidic, 2008.

One of the cargo ships docked at Tanjung Perak that day was among the 460COSCO SHIPPING Lines – Company profile container vessels owned by COSCO Shipping Lines, a Chinese state-owned marine transportation company. The East Asian country, home to the world’s largestUnited Nations Trade and Development – Merchant fleet by flag of registration and by type of ship, 2025 merchant fleet, has sought, since the launch in 2013Ministry of Foreign Affairs People’s Republic of China – Full text of President Xi's speech at opening of Belt and Road forum, 2017 of the Belt and Road Initiative, to intensify seaborne flows across major maritime corridors. Annual international maritime trade volumes had already nearly quadrupledUnited Nations Trade and Development – Review of Maritime Transport, 1968-2025 in the four decades leading to 2024, driven in part by the rise of Chinese manufactured goods exports. Each additional voyage increases threats to marine mammalsEncyclopedia of Life – Java Sea Species List, 2019, including in the Java Sea, where dozens of species of whales, dolphins and dugongs live.