Is there a ferry to the Cíes Islands from O Grove?
No.
There is no line to the Cíes Islands from O Grove. From O Grove there are boats to A Toxa island and ría cruises visiting the mussel rafts, but none to the Cíes.
The nearest port that works
From O Grove, the practical move is to head to Sanxenxo and board there: €32.50 per ticket and 1 departure a day in high season.
11:15
If you want more flexibility, Vigo runs up to ten daily departures in summer and is the cheapest port.