I’m guessing this is something that has been puzzling a lot of people – I’ve gotten a lot of hits recently from people googling some variation of ‘Islam’ and ‘burial’, and I got asked it twice at the same time.
So as Asher and Uzza asked: “OBL was buried at sea according to Islamic custom” Say whut?
This is going to be a first go at a partial answer, as it turns out there’s a much larger dearth of information than I expected. Yay unexpected research projects!
There’s an obvious pragmatic reason that bin Laden was buried at sea – tombs in Muslim tradition often become shrines and pilgrimage sites, so basically burying him at sea means that anyone who wants to visit his tomb will have to go jump in the ocean. But the question still remains whether it was acceptable under Islamic law to do so.
And my best answer is: I can’t find anything to say that it isn’t permissible, but also it doesn’t seem recommended under any circumstance except for those lost at sea.
To be fair to the White House, I think what they meant by their announcement was that his body had been prepared according to Islamic custom – it was washed and wrapped in a shroud, and prayed over by an Imam, which, according to the hadith (the sayings of the Prophet (s’lm) and, along with the Qur’an, the basis for Islamic law) is really all that’s necessary for a funeral service.
As for depositing the body in the ocean, as far as I can find, there’s no reference to burying people at sea at all in the hadith. But there are a few cases that I think imply that it would be permissible. The first is the case of people lost at sea – there are several hadith that praise Muslims for serving in the Muslim naval force, which make no reference to burying the bodies, but which do say that those who fight in the Muslim navy die as martyrs, implying that their burial at sea is equivalent to a martyr’s burial. But again, this would more clearly apply to those lost at sea.
The other case is of people buried in transit, which is the reference made by the White House, as well. There is an injunction in the hadith that a body should be buried as soon as possible, and it has always been acceptable to bury a Muslim in foreign territory. In fact, several important generals and commanders from the period of the Islamic expansion were buried abroad – famously, the Muslim commander Maslama is supposed to be buried in the outer side of the Theodosian walls at Constantinople, as he died during the Muslim siege of the city in the late seventh century. But again, in most of these cases, the person is buried where they fell – on land if they died on land and by sea if they died at sea. I see no particular reason why it should be impermissible to bury them either on land or at sea where they died, but there’s no reference to it, one way or another.
As a fun tangent, I have now discovered that apparently worshiping at graves and the construction of shrines and monuments over tombs, all of which are common in the Muslim world, are apparently banned according to the hadith, on the basis that worshiping tombs could be a path to polytheism, as people worshiping other people instead of focusing on God.
That’s the hadith. What I haven’t done yet is check the actual regulations of Islamic law. As bin Laden was a Wahhabi, he would have subscribed to Hanbali law. Annoyingly, Oxford doesn’t have a translation of Ibn Hanbal’s writing, and I just don’t have the time to read the Arabic edition right now. I am really intrigued about this question now, though, and hopefully I will be able to come up with a more definitive answer soon.
 I still looks weird to me to write his name that way, but as that appears to be now the standard English version, I’m sticking to it. In Arabic, ‘bin’ is actually a contraction of ‘ibn’ meaning ‘son’ or ‘son of’. Normally when using a longer version of a person’s name, you contract ‘ibn’ to ‘bin’, but when just using the ‘son of’ portion, it reverts back to ‘ibn’. So really he should be either ‘Osama bin Laden’ or ‘Ibn Laden’.
 Actually, it’s possible no translation exists. Islamicists are notoriously lazy about producing editions and translations, which is particularly annoying as we have such a small corpus. If every Islamicist edited and translated one text, we could get through most of the core corpus in this generation. But we don’t. Not that I’m bitter or anything!