It is 45 minutes of open Atlantic from Peniche. With a swell the crossing rolls (reviews mention waves that were “quite impressive”) and the caves are only visited in calm seas. Check this before choosing your day.
Few clouds
Indicative reference based on OpenWeatherMap data for the island’s coordinates. Whether to sail and whether to enter the caves is always the operator’s call. If you get seasick, sit at the back and watch the horizon: it is 45 minutes.
Another trip by boat
The Cíes Islands, off Vigo, work much the same way: a national park, a daily cap and an authorisation to get before the boat. Boat to the Cíes Islands →