Surface waters in a 4-mile radius above the dragon crab's lairs are prone to strange currents, unpredictable winds, and even some whirlpools. The dragon crab has no control over these and they cannot be used to its direct tactical advantage, but they increase the difficulty of seagoing navigation by 5 for any vessels or swimming creatures that attempt to traverse them. Local sea life has adapted to these strange currents; anything born within the 4-mile radius of the effect suffers no penalties in navigating it.