"Nice boat" is a meme spawning from the imageboard 4chan from the cancellation of the regular broadcasting of the anime "School Days" in Japan. The program was then replaced with relaxing images of scenery and classical music. A boat was pictured, and someone commented "Nice boat".
The full definition:
The day before the final episode was scheduled to air, a sixteen-year-old girl killed her father with an axe in Kyoto. In response, TV Kanagawa replaced the episode, which was known to contain similarly violent material, with half an hour of scenery and classical music to avoid association with the murder. Other stations airing the anime followed suit, except for AT-X, who remained indecisive at the time. In the following week, 0verflow announced that a screening of the episode would take place in the Tokyo area as part of the release of the series first DVD volume, and would require a copy of either the PC game or Summer Days PC game for admission. However, AT-X announced that they would air the last episode on September 27, 2007, with minor alterations in airing times. The screening of the episode that 0verflow announced showed the uncut version of episode twelve, including the blood color change from black back to red, adding back all sound effects that were removed from the broadcast version, and fewer flashbacks. The uncut version of the episode was included in the DVD release on February 27, 2008.
The sudden swap of the last episode to scenery footage led to shock and confusion among the fans. A contributor of the English-speaking 4chan image board posted screenshots of the episode, dryly commenting that the "last episode of School Days is live action" and writing "Nice boat" next to an image of M/S Skagastøl, a Norwegian Fjord1 ferry. The phrase "Nice boat" immediately became an Internet meme and reached massive proportions in Japan, spreading via screenshots of the 4chan thread and a flood of "nice boat" comments on Nico Nico Douga videos of the scenery footage. It ranked tenth in Yahoo! Japan's keyword search ranking for the week of September 17 to September 23, 2007, and appeared as a hidden message in the first episode of the anime Ef: A Tale of Memories.. The phrase was so well-known among fans that 0verflow decided to name its booth "Nice boat" for the Comiket 73 in December 2007, selling "Nice boat" merchandise along with its normal line of specialty items.
(Any boat docked or moving)
Anon: Nice boat.