Italy navy patrols the hot zone off Libya
We spent much of the day sailing south-west towards the Libyan coast, under a baking hot sun.
It hasn't always been like this. The day started cloudy and choppy, a swaying ship making the three of us in our BBC team a little queasy.
Now it's calmed down, but the seas off Libya have high waves, we're told. "Good for me," said the captain. "The migrants are less likely to launch."
We're now in the area the navy calls the "hot zone", where they are most likely to pick up migrants.
We're now aboard a frigate, the Bergamini, to which we were transferred by helicopter from the Italian naval ship Etna.
This is the sharp end of the operation, where lives are saved - and where we've learnt the specifics of this complex mission.
The ship is under orders to save lives. Whether boats are in trouble or not, they will try to intercept them and pick up the passengers.
The sea, outside territorial waters which extend 12 miles out from the coast, is divided into areas of operation in which certain countries are in charge of any search and rescue that is needed.
The Bergamini, as part of the Italian navy's Mare Nostrum (Our Sea) operation, is patrolling an area that falls under the responsibility of the authorities in Malta and Rome.
"The key is saving these people," says Lieutenant Giuseppe Bisceglia, who is one of the first rescuers to arrive alongside the migrant boats that get into trouble.
"We try to start to have some communication with the vessel. Sometimes we can, sometimes not. We launch a small boat. I get on it."
He has watched as parents and relatives practically throw their children at the Italian navy boat. "It's a delicate operation."
So now, for us, just like the crew, it's a waiting game.
Perhaps in the few days we have on board we will be present as they rescue migrants - perhaps not. But the flow overall shows no sign of easing and all the signs of accelerating.
As the people waiting on the Libyan coast for good weather learn that the navy is waiting here to pick them up, more may set off on this hazardous journey.