Will I lose SouthESIM signal on the ferry between Antigua and Barbuda?

While your SouthESIM will provide strong signal when you're near the coasts of Antigua and Barbuda, particularly around the ports, it's quite common for mobile signal to become intermittent or drop entirely when you're out in the open ocean during the ferry crossing. This isn't unique to eSIMs but applies to all mobile networks. You can expect to reconnect once you get closer to land again, so enjoy the sea views and disconnect for a little while!