Spanish authorities say they've rescued 593 migrants at sea in just one day.
The Spanish Maritime Safety & Rescue Agency, also called Salvamento Marítimo, said it recovered the people on 15 boats Wednesday in the Strait of Gibraltar and the Alboran Sea, the western part of the Mediterranean Sea.
Among the migrants were 39 minors, according to Spain's state-owned public broadcaster RTVE.
As of last week, the United Nations' International Organization for Migration says 8,385 migrants have arrived in Spain by sea so far this year, and 121 people have died along the western Mediterranean route. That's up from 2,476 arrivals in the first half of 2016.
Migration by sea to all of Europe, however, declined greatly from 2016 — mainly due to a drop in the number of arrivals to Greece. The IOM says the vast majority — 83 percent — of migrants entering Europe by sea this year landed in Italy.
But Spain could soon overtake Greece in having the second-highest number of migrants arriving in the country by sea, after Italy.
"Given the crackdown on migration from Libya, it seems natural that many would forsake the dangerous desert crossing to Libya and choose to cross from Morocco," IOM spokesman Joel Millman told the Financial Times.
More than 12,000 migrants have come to Greece by sea in 2017, sharply down from more than 161,000 at the same point last year.
At its narrowest point, the Strait of Gibraltar separates Spain and Morocco by about 8 miles. Many migrants choose to attempt the crossing on "cheap, child-sized paddle boats without motors that allow them to bypass people smuggling networks and their fees," the BBC reports.
An onlooker captured video when a small boat full of migrants landed on a tourist beach in southern Spain last week:
Migrants in Morocco also attempt to enter Spain by land at Ceuta and Melilla, two cities that are Spanish territory but physically part of Africa. Thousands of people attempt to enter Spain each year by scaling or swimming around large fences that separate the territories.
As of Aug. 13, the IOM says total arrivals in Spain were almost 12,000 this year, while more than 124,000 migrants arrived in all of Europe.
More than 2,400 migrants died in the Mediterranean each year in the last four years, the agency says.