Random explosions while on an island

I was in the middle of The Art of The trickster tall tale. I had just completed the three riddles on Plunder Valley and had retrieved the keg from the ground. Upon picking up the keg and taking it down the valley on the island I heard a series of loud explosions. They didnt sound like cannon ball explosions but I still assumed someone was attacking my ship, maybe with powder kegs. As I was taking the keg down the valley, I see massive explosions, constantly, blocking my exit. I thought they might cease as I kept going but they didnt and one explosion instantly killed me without reducing my health or setting me on fire, I just keeled over and died. Upon respawning the explosions had stopped and everything returned to normal.
If it's important I tried to take the light from the flame on the ferry and there was nothing to take.
I've looked it up and found nothing, only people running boats into kegs on the seas accidentally, nothing about unexplained explosions on the island.