The Coastguard says it was alerted to reports that a woman wearing a life jacket was missing at sea at 1.30pm this afternoon.
The disappearance followed a collision between a yacht and a dredger, with one other person pulled from the water by a rescue boat before raising the alarm.
More top news
The Duke of Cambridge said his children were beginning a "lifetime of friendship" with Canada as they began their tour of the country.
When and where are they on, and how do they work?
What better, more dramatic spectacle has there ever been on American television?