Thousands of tourists have been evacuated from offshore islands ahead of category five Typhoon Nepartak.
The super typhoon packed winds of up to 263km (163 miles) an hour, some 780km south-east of Taiwan's Hualien city on Wednesday, officials said.
They also warned of the risk of flooding and mudslides as high winds and lashing rains were expected.
"As the typhoon kept gaining strength and approaching Taiwan over the past three hours, the Central Weather Bureau decided to issue a sea warning at 14:30 local time (06:30 GMT)", senior forecaster Chen Yi-liang told AFP.
(BBC News)