Climate policies were top of mind as people began a march into Spain from the French border town of Hendaye.
Signs carried by the protesters included images of Earth, blaming G-7 leaders for recent climate policies.
Thousands of extra police were at the ready, expecting some pushback from protesters throughout the weekend over the gathering of world leaders.
According to some local reports, fewer people than expected showed up to protest ahead of the meeting.
French President Emanual Macron earlier in the Summer stated he had the intention of including a discussion on climate change for the summit.
Information from The Associated Press contributed to this report.