"A man asked the prophet ﷺ: 'O Messenger of Allah, we travel by sea and we take a little water with us, but if we use it for Wudu', we will go thirsty. Can we perform Wudu' with seawater?' The Messenger of Allah ﷺ said: 'Its water is a means of purification and its dead meat is permissible.'"  

أَخْبَرَهُ أَنَّهُ سَمِعَ أَبَا هُرَيْرَةَ يَقُولُ سَأَلَ رَجُلٌ رَسُولَ اللَّهِ ﷺ فَقَالَ يَا رَسُولَ اللَّهِ إِنَّا نَرْكَبُ الْبَحْرَ وَنَحْمِلُ مَعَنَا الْقَلِيلَ مِنَ الْمَاءِ فَإِنْ تَوَضَّأْنَا بِهِ عَطِشْنَا أَفَنَتَوَضَّأُ مِنْ مَاءِ الْبَحْرِ فَقَالَ رَسُولُ اللَّهِ ﷺ هُوَ الطَّهُورُ مَاؤُهُ الْحِلُّ مَيْتَتُهُ