"Cruising is booming – 2023 ticket sales have surpassed historic levels and 2024 has seen the launch of the largest cruise ship ever built. "But as cruise tourism's popularity has increased, so have the pollution problems it brings. To customers, it may not be evident that any problems exist, since some cruise line companies claim to be becoming more climate-friendly. "The truth can be quite different. Josh Toussaint-Strauss interrogates what impact the world's biggest ships are having on the planet."