expression
by a comfortable margin; by a wide margin
Fixed expression used when someone wins or leads by a clear, decisive margin, often in sports or competitions. The phrase literally means 'opening the water widely', evoking a gap like a stretch of water between boats.
彼は大きく水をあけて一位でゴールした。
He finished first by a wide margin.
そのチームは大きく水をあけて優勝した。
That team won the championship by a comfortable margin.