The boat, which is operated by a charity known as Proactiva Open Arms, usually patrols between Libya and southern Europe with a mission to aid migrants who find themselves in trouble while trying to cross the sea into Europe.
According to the charity, the 87 migrants who were dropped off at the Spanish port of Algeciras, were rescued on 2 August from an inflatable raft that was floating due to a broken motor.
“We came across the raft where the people were in a very bad state and very afraid that we were a Libyan boat and we planned to return them to Libya,” Open Arms mission head Ricardo Gatti said during a news conference in Thursday.
Among those saved include 84 migrants from Sudan, one Syrian, one Egyptian and a Gambian. There were also 12 children on board.
Most of the migrants will be processed in Spain before they are granted refuge in Europe, while a source told Reuters that around 20 of them will be taken in by France. Those who do not meet the stipulated requirements will be sent back home.
Irregular immigration across the Mediterranean has fallen dramatically, with about 60,000 people making it to Europe across the sea to date this year compared to over a million in 2015.
The International Organization for Migration says that Spain has seen arrivals jump to 23,741 by August this year compared to 8,677 in the same period in 2017 as countries such as Italy clamp down on arrivals along its coast.