I've found that while I'm walking around with a damaged surfboard in my inventory, sometimes the animation for bits breaking off will play, complete with bobbing in the water and then sinking.
Possibly related, but I think I've seen a couple of seagulls land on land (during mild season) and sit down, making the water-ripple animation as if on sea.
Steps to Reproduce
Play Walani, damage Surboard a bit, wait around for some seagulls.
Play Walani, damage Surboard a bit, wait around for some seagulls.
A developer has marked this issue as fixed. This means that the issue has been addressed in the current development build and will likely be in the next update.