i'm on board the portia with fisherman matt coker. he's seen how the english channel has changed. each year, his radar picks up more and more boats. this is the shipping lane here. that's another large... that's a border force boat? that's another border force boat. he's heading out there fast, so there's obviously another migrant boat been spotted out here. it's been a long, hot summer, perfect conditions for migrants to cross the channel... ..and for the people smugglers charging thousands to bring them to the uk. there'll be a0 or 50 on each boat. they're all in the same boats now, they're all these big, long, black dinghies, which are about sort of seven or eight metres long, so they normally have about a0 or 50 on board, so... so it's a couple of hundred already today. 0h, easily. easily a couple of hundred already. and as i say, you've got one, two, another... ..at least three out here, so there's another 150. you know, you're probably up to... you're probably going to be up to 600 or 700 by before midday today. almost 90% of those arriving this year are men. more than 20,00

coker wasn't as lucky. he drowned in a rip current in lake michigan while swimming with friends. >> matt was a good swimmer.o the beach that often. >> they were knee deep. we didn't know anything about red flag warnings, rip currents. >> we need to understand even though you know how to swim, you could become a drowning victim. >> reporter: with that in mind, i jump in. one of the most common mistakes is trying to swim right back to shore by swimming against the current. the thing with the rip current, it is moving as fast as an olympic swimmer. so unless you're michael phelps, you're probably not going to beat it. >> you're swimming against this treadmill and you're probably not even making progress. you're going backwards. >> reporter: waves are crashing over your head. you start to exhaust yourself and that's when it is harder to stay above water. instead, experts say the first thing to do is flip and float. this will help keep you calm and it is critical since they say the first stage of drowning is panic. take a breath. this is when you have the time and capacity to start thinking about your next move.