The afanc raises the front part of its body out of the water and brings it crashing back down against the surface. This generates massive waves up to 30 feet tall that may capsize boats and ships within 100 feet of the afanc. Boats and ships less than 20 feet long automatically capsize. A creature steering or guiding a boat or ship over 20 feet long must succeed on a DC 20 Dexterity or Strength check or its boat capsizes. A creature proficient in Vehicles (water) may add its proficiency bonus. A non-aquatic creature in the water within 100 feet of the afanc must succeed on a DC 20 Dexterity saving throw or take 21 (6d6) bludgeoning damage and be stunned until the end of its next turn.