It seems you don't get this achievement when entering instances and instances are the only way to get to that zone it seems.. Tried 3 different missions now and all the same. No update.
The second post in this should help you. the one about The Open Sea: Hired Hands https://forums.daybreakgames.com/eq/index.php?threads/the-open-sea-traveler.208209/
Thank you, but not quite sure it's the same or maybe something has changed. As i read Good's post(some years old now) he's talking about a missing quest update. Though he also mentions Merchant ships for Open Sea Traveler achievement. But there is no Merchant ships for Open Sea Traveler achievement, just Open Sea Traveler achievement. I'll take a look it again, when i'm back from work.