Bog Water can only be found in Swamplands. Currently (as of R27 in January 2016) it is not poisonous for player-characters to swim in, or rather wade in, as it usually is only 1 block deep, except for parts where it might flow down into caves. While staying in Bog Water (if a sufficient amount of Bog Water is around) the air above appears greenish. Reeds, Cattails and Lilypads can be found in Bog Water in "naturally" generated Swamplands, however no more of these seem to spawn in Bog Water over time. Bog Water is a liquid that requires Diamond Mining Cell to forage.