They were the preeminent fishermen of the server, and had created an AFK fishing farm before such things were outlawed. Most of the enchanted books which have spread around the world, especially prior to the villager trading boom after the 1.14 update (see 1.14 Troubles) were fished by the Water Boys.
The Water Boys were decidedly apolitical, believing the debate and discussion engaged in by other countries, especially Montrose, were needlessly confrontational and were creating mountains out of molehills. Strangely, this non-confrontational belief system led them to agree with the anti-Montrose "might makes right" and "let things lie where they fall" sentiments of the Dark Forest Investment Co., culminating in the Water Boys joining the South Sea Coalition.
The Water Boys left the server as a reaction to a pair of meta events which they vehemently opposed: the addition of the Factions plugin, and the banning of Hatty_Hominid.