Compared to flying to a destination and staying in a hotel, cruising almost always has a far higher emissions profile, according to research by Comer and others. A five-night, 1,200 mile cruise results in about 1,100 lbs of CO2 emissions, according to Comer.

When comparing the two, cruises are generally considered worse for the environment on a per-passenger, per-kilometer basis. While aviation is a massive contributor to global CO2​ emissions and high-altitude warming, a cruise ship is essentially a "floating city" that produces immense amounts of waste. Beyond carbon emissions from burning heavy fuel oil, cruises generate "black water" (sewage), "gray water" (sink/shower runoff), and significant plastic waste. In 2026, studies show that a single person on a five-day cruise can have a carbon footprint three times larger than if they had flown to their destination and stayed in a hotel. Furthermore, cruise ships impact delicate marine ecosystems through anchor damage and underwater noise pollution. While the aviation industry is moving toward Sustainable Aviation Fuel (SAF), the cruise industry’s transition to Liquefied Natural Gas (LNG) is often criticized for "methane slip," which can be even more damaging to the atmosphere in the short term.