These people are protesting against Spain's annual running of the bulls festival because bulls are executed in a cruel and violent way each year.
The protesters poured red blood-like liquid all over themselves while standing in a town square, wearing only underwear.
See also: Bull running festivals in Spain: Should they be banned?
See also: Two British tourists gored at Pamplona's Running of the Bulls
The bulls are forced to run in the race by electric shocks and they are beaten and harassed by the 'corridors'.
The Pamplona San Fermin Festival is a Spanish tradition that includes bull running and bull fighting.
The purpose of the bull running is to transport them into a bullring to be slaughtered in a 'prolonged, ritualistic fashion'.
This isn't the first time there have been protests, they occur every year on 5 July which is the day before the festival starts.
About 250,000 bulls are killed every year in the festival and AnimaNaturalis wants it to end.
AnimaNaturalis is an animal rights organisation that works to promote and protect the rights of animals, specifically in Spain and Latin America.
Kirsty Henderson is PETA's campaign director for the festival, she explained that the festival led to bulls being executed in a 'violent and bloody way'.