Juan Medina, a photojournalist with Reuters news agency, spent 29 days on board a rescue boat off Libya, documenting the search for those lost at sea.
Open Arms is a retired 36m tugboat operated by the Spanish charity Proactiva Open Arms. It patrols an area where hundreds of thousands of people have embarked on treacherous crossings to Europe in recent years.
Almost 1.8 million people have migrated across the Mediterranean from the Middle East and Africa since 2014, according to UN figures.
A dramatic moment during Medina's time on board the Open Arms was the rescue of Josepha (seen below and at the top of the article). She was the only survivor plucked from a deflated rubber raft where the bodies of a woman and a four-year-old boy lay.
Josepha was in a state of shock when she was taken aboard and treated by doctors on 17 July. She said she was from Cameroon and had spent the night clinging to the wreckage, singing hymns and calling to God.
Ahmed, 38, seen below, was rescued with his 13-year-old son in early August.
He told Medina that he and his son had travelled from Darfur, Sudan. In the Libyan city of Sabratah, west of Tripoli, they and others were kidnapped and held captive for seven days.
Managing to escape through a window they went to the town of Garabulli, about 130km (80 miles) to the east, and waited over five weeks to pay 2,000 dinars (£1,114, $1,438) each and got on a rubber boat.
After sailing 15 hours the boat broke and they were adrift for three hours.
At night they saw light approaching. Ahmed told Medina: "There was a moment of great fear and nervousness because we did not see well and the worst thing that could happen is that the Libyan patrol arrived and forced us to return to that hell.
"But then we heard from one of the two fast speedboats that approached: 'We are friends, we are a Spanish rescue ship.' We began to shout with joy."
Ahmed continued: "Some did not understand the message, perhaps because they do not speak English, and thought that one of the two boats was the Libyan coastguard and threw themselves into the water, preferring to risk drowning than return to Libya.
"Luckily we are all alive. We have a new opportunity."
Medina photographed other migrants rescued from the sea by the Open Arms.
Chuol, 17, from Sudan, is seen below listening to music.
Chuol takes a shower, below.
Amjad, 23, from Sudan, sleeps on board the Open Arms, below.
Mohamed, 23, also from Sudan, reads a book: An Illustrated Introduction to Europe for Migrants and Refugees.
Yuosef, 28, from Sudan, below, stands on the Open Arms and looks out at the sea.
Photos by Juan Medina.