Antonio Argüelles, 58, rose near dawn Thursday hoping for good fortune.

He had arrived in Donaghadee, Northern Ireland, from Mexico City a few weeks before to prepare to swim 21 miles of the frigid, tempestuous North Channel between Northern Ireland and Scotland.

He’d already knocked off six of the seven arduous channel crossings that make up the so-called Oceans Seven, open water swimming’s answer to climbing the Seven Summits of mountaineering. And if the weather cooperated, he would have a chance to complete this crossing and become the first Latin American, the seventh person ever and the oldest to complete the Oceans Seven.

Nature seemed to have other plans. Argüelles recalled that morning later in an interview by telephone. As he sipped his coffee and stared to the horizon, all he could see were dark, foreboding skies spreading a summer rain over a gray-green sea.

To complete an official crossing of the North Channel, a swimmer must hire a boat and an official observer, or referee, through the Irish Long Distance Swimming Association.