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water's edge; shore; waterside
「水際」 has another reading with different meanings.
水際に立つ灯台が夜の海を照らしていた。
A lighthouse standing at the water's edge illuminated the night sea.
子どもたちが水際で小さな魚を追いかけていた。
The children were chasing small fish at the water's edge.
水際対策を強化してウイルスの侵入を防ぐ方針だ。
The policy is to strengthen border measures to prevent virus entry.