Travel insurance for Santa Maria, in the Azores, is worth arranging before you travel, and while a European health card helps, the islands' remoteness means a serious case can involve an expensive transfer to the mainland. The Azores are an autonomous region of Portugal in the mid-Atlantic, and Santa Maria is one of the smaller islands, so cover for evacuation and repatriation matters more here than for a mainland trip.
Your health card helps, but is not enough
The Azores are part of Portugal and the EU, so an EHIC or a UK GHIC gives you access to medically necessary state healthcare. It is worth knowing that the Azores run a separate health system from mainland Portugal, with good hospitals on the larger islands, at Ponta Delgada and Angra. The card, though, is not a substitute for travel insurance: it does not cover private treatment, repatriation, or, importantly, the cost of an air-ambulance transfer to the mainland, which is exactly the sort of cost a small-island trip can generate.
Remote care and evacuation
Santa Maria itself is a small island, so a complex case may be transferred to a larger Azorean hospital or, for serious emergencies, to Lisbon or Western Europe by air ambulance, which can cost twenty thousand euros or more uninsured. Hospitals in the Azores also generally require payment up front, even if you hold insurance, so you claim the cost back. For those reasons, travel insurance with an emergency-evacuation limit of around 250,000 euros is a sensible level for island travel here.
Choosing a policy
Carry both if you have them: the EHIC or GHIC for state care, and a travel policy for repatriation, private treatment, and evacuation. The Azores are seismically active and have a wildfire season, so natural-disaster and delay cover are worth having, and if you plan hiking, diving, or whale-watching trips, confirm those activities are covered. Subscription-style cover such as SafetyWing suits long trips, while a per-trip policy is simpler for a single visit. Buy the cover before you leave home, because most insurers will not cover a trip once it has already started.