Nice Boat refers to a meme spawned from a 4chan comment about a Japanese programming decision to air pleasant stock footage rather than the final episode of the anime School Days due to the episode's similarity to a recent tragedy in the country. Amidst the outrage over the decision, a 4chan commenter wrote "Nice boat" about a portion of the stock footage, quickly turning into a meme in the community.
In September of 2007, on the day before the airing of the final episode of the School Days anime in Japan, a 16-year-old girl killed her father with an axe in Kyoto. Due to an extremely similar scene present in the episode and to avoid relation to the axe murder, TV Kanagawa replaced the episode with a half-hour of unrelated scenery while "Air on a G String" played in the background. Included in the footage was a Norwegian ferry (shown below).
Among the shock and rage expressed among fans, a 4chan user commented "Nice Boat," referring to the Norwegian ferry shown in the replacement footage (shown below).
The phrase quickly became a meme, though it is more popular in Japan than in English speaking countries. The scene spawned multiple pieces of fan art blending School Days and the phrase "Nice Boat" (examples shown below).
In 2020, an episode of Interspecies Reviewers was cancelled and replaced with footage of boats, leading some to speculate it was a reference to the "Nice Boat" meme.