sarah morris has been there to find out more.is a routine, every morning spanish customs officers take to the sea looking for traffickers. in the gibraltar strait, 100 customs officers patrolled the coast seven days a week. they are after speedboats carrying drugs. ththey are 12 meters long and extremely powerful. >> here in the strait it is a permanent race, because response time is minimal but the african coast is nearby. they are so fast. we to send out a list to catch them. reporter: every year, the cannabis grows. lester, 130 tons were seized, three times more than in 2016. by sea a round-trip, between morocco and spain takes less than one hour. >> they are like flies. they move around everywhere. they are unpredictable and the coast is difficult to navigate, with a lot of traffic in the ports. that is why we put a camera system in. with the sea patrol and helicopters. reporter: this year, customs has their own fastest speedboats to stop the drug pushers reaching the bay. boats and helicopters chases are common, because the