It’s one crocolisk normally doing it. near the first bridges.
To avouid this specific death: Kill the rare elite Blackmoss the Fetid. The Timberling from his heart - quest object - is enough to keep the corcolisk occupied long enough for you to be out of range when it dies.
I hop off the boat to Theramore just as it ports, then start to swim. Run on terrain as much as possible. It takes roughly 25 minutes for me. I stream a show or listen to a podcast to chase the boredom away.
People who;
A) Don’t know about the skip
B) People who can’t play all the time and a 15 minute difference can literally be the difference between playing on a day or not.