Is it permissible for a Muslim to perform ghusl for prayer with seawater when necessary?

It is permissible for a Muslim to perform ghusl or wudu with seawater, even if not in a state of necessity, because seawater is pure, as the Prophet, peace and blessings be upon him, said: "Its water is pure, and its dead (creatures) are lawful." Seawater also falls under the general meaning of the Almighty's saying: "And if you find no water, then perform tayammum."