Hadith: Its water is pure and its dead animals are lawful (to eat)

عن أبي هريرة رضي الله عنه قال: سأل رجل النبي صلى الله عليه وسلم فقال: يا رسول الله، إنا نركب البحر، ونحمل معنا القليل من الماء، فإن توضأنا به عطشنا، أفنتوضأ بماء البحر؟ فقال رسول الله صلى الله عليه وسلم : «هو الطَّهُورُ ماؤه الْحِلُّ مَيْتَتُهُ».
[صحيح] - [أخرجه أبو داود والترمذي وابن ماجه والنسائي ومالك والدارمي وأحمد]

Abu Hurayrah (may Allah be pleased with him) reported: A man asked the Prophet (may Allah's peace and blessings be upon him): "O Messenger of Allah, we travel by sea and carry with us a little water. If we made ablution with it we would become thirsty. Can we make ablution with the sea water?" The Messenger of Allah (may Allah's peace and blessings be upon him) said: "Its water is pure and its dead animals are lawful (to eat)."
Sahih/Authentic. - [Ibn Maajah]

Explanation

In this Hadīth, the Messenger of Allah (may Allah's peace and blessings be upon him) clarified that sea water is pure and thus it is permissible to use it for purification, and that it is lawful to eat dead sea creatures, like dead fish and so forth.