It's been confirmed the Houthis sank two ships in in the Red Sea, the Rubymar and the Tutor: https://apnews.com/article/houthi-rebels-ship-attack-red-sea-yemen-bfa7d321e55c5bb59b268b82ef3c56ba

This market will resolve YES if they sink a third ship before 2025. Sink means to damage so catastrophically it sinks on its own, or is not salvageable so it is purposely sank by a third party. Small ships are excluded, the ship must be over 100 feet long.