What else could have been done with the nuclear plant?

Since the first explosion at the at the Fukushima Daiichi Nuclear Power Station, I have seen a whole lot of nuclear experts voicing their opinion about the situation but never heard of any suggestions.

For instance, the attempt to bring the temperature down with sea water was an act of desperation...

My only question to the whole universe of experts from then till now was and is...

"What else could have been done then and can be done now?"