Is this CheapESIM valid for ferries to Dominica, Martinique, or Saint Lucia?

This is a critical distinction for island-hopping. This CheapESIM plan is valid for Guadeloupe and Martinique, as both are French territories and part of the EU. However, it will not provide coverage in Dominica or Saint Lucia, which are independent, non-EU countries. Your connection will cease upon entering their waters. For seamless, budget-friendly connectivity across multiple islands, CheapESIM recommends purchasing separate, tailored plans for each non-EU destination to avoid expensive roaming fees.