Boat being a more environmentally friendly form of travel is bogus from wiki:
The environmental impact of shipping includes air pollution, water pollution, acoustic, and oil pollution.[1] Ships are responsible for more than 18 percent of some air pollutants.
It also includes greenhouse gas emissions. The International Maritime Organization (IMO) estimates that carbon dioxide emissions from shipping were equal to 2.2% of the global human-made emissions in 2012[3] and expects them to rise 50 to 250 percent by 2050 if no action is taken.[4]
Also shipping disturbs ocean life. The accoustics confuse whales and dolphins and can result in them becoming beached or losing communication with their pods Large ships can also cause ocean pollution.