From "SEALAND, HAVENCO, AND THE RULE OF LAW", James Grimmelmann, New York Law School:

A serious fire broke out on Sealand on Friday, June 23, 2006. The only person on Sealand at the time, a security guard, tried and failed to put out the fire. Suffering from smoke inhalation, he had to be airlifted out to Ipswitch Hospital on the mainland by a Royal Air Force helicopter. More than twenty firefighters responded, from a mix of private and governmental groups. A tug sprayed Sealand with water as smoke billowed hundreds of feet into the air.

Michael Bates, who had been visiting his parents in Spain, moved quickly to reoccupy the platform, boarding it with his sons James and Liam on Sunday, June 25. The damage, however, was extensive, estimated at half a million pounds. That total doesn't include the costs of putting out the fire, for which the rescue services decided not to charge Sealand. Charred debris and rusted metal were everywhere, and large quantities of water from the firefighting operation had pooled in the bottom of one of the legs. Over much of the next year, work crews cleaned out the mess, repaired the living quarters, and made Sealand habitable again. A post-fire website, now offline, referred to an "exclusive building contract," and sought investors for the rebuilding for "business ventures that are legal both in the UK and Sealand."