Hover does not let you pass 'blocking' terrain, but what about water ? Its 'impassible' but does not block line of sight, so why shouldn't Hover let you float over water ?
Because its affected by rough terrain. To ignore rough terrain you need flight which is a different card.
The reason for this is that we don't have rules for what happens if you drop into water, i.e. if you lose your hover attachment while over water.
