Three migrants have arrived from Nigeria in the Canary Islands after an 11-day journey at sea sitting at the helm of an oil vessel just above the water level, the Spanish maritime rescue services said on Twitter, DPA and Agerpres reported.

The Althini II arrived at the port of Las Palmas on the island of Gran Canaria on Monday and the three were immediately taken to hospital.

Every year, thousands of people embark on a dangerous sea journey from the coast of Africa to the Canary Islands, which belong to Spain. Migrants are usually sent in small open boats to their destination, located at the nearest point about 100 kilometers away in Atlantic waters.

According to the UN, the number of arrivals via this route has risen to almost 15,000 this year, and the UN’s International Organization for Migration has reported that more than 1,500 migrants have died or gone missing at sea. The death toll is believed to be much higher than these figures.