Rule Clarification: Underwater Movement & Vision
Last session there was some discussion of how much distance could be covered swimming with the Manta Ray Cloak. Based on the DMG rules, here is a quick summary:
1. Underwater movement is measured as in dungeons (i.e., feet rather than yards), so 18″ movement means a maximum of 180’/rnd.
2. That comes out to 1800’/turn, or 600 yards/turn.
3. While a full turn of rest each hour doesn’t make sense while swimming in this way, I think periods of less strenuous activity equal to a turn of rest over the course of the entire hour makes sense. That means movement is 3000 yards/hour, or 1.7 miles/hour.
Since the Midmark ships will arrive near Grell’s hidden cove at around 2pm, that leaves four hours for Chuq to check things out before dusk. In that time, he can swim just under 7 miles (meaning the ships can anchor about 2.5 miles out from the cove).
Another quick point: Per the DMG, maximum vision distance underwater is 100′ (decreasing 10′ per 10′ of depth — i.e., at 30′ depth you can see 70′).