The Saudi-led coalition battling Yemen's Houthi forces has destroyed two explosive-laden boats that the Iran-aligned group planned to use in an "imminent" attack launched from the Red Sea port of Hodeidah, Reuters reported Saudi state media as saying.
The coalition in separate statements also said it intercepted and destroyed three armed drones launched towards southern Saudi Arabia, including the city of Khamis Mushait.
The Houthis, who ousted Yemen's internationally recognised government from the capital, Sanaa, and now hold most of north Yemen, have kept up missile and drone attacks on Saudi Arabia after Riyadh last week presented a new peace initiative.
US Special Envoy Tim Lenderking on Thursday returned to the region to push for the initiative, which includes a nationwide ceasefire.
The Houthis want the coalition to fully lift its sea and air blockade on areas the group controls.
The conflict, seen in the region as a proxy war between Saudi Arabia and Iran, has caused what the United Nations says is the world's largest humanitarian crisis.
The Houthis say they are fighting a corrupt system and foreign aggression.