Do NOT attempt to recover the data yourself. This will do more damage to your data and makes it more difficult to recover when it eventually gets to a data recovery specialist.
When hard disk drives get wet, the 'heads' can get stuck to the platters. When the hard drive is powered up in this state the disk tries to spin up and the heads literally get ripped off causing damage to the platters - the place where all the data is stored. 2 - Do NOT DRY the hard disk drive out. Although this may seem paradoxical - this will nearly always destroy the platter of the hard disk thus making your data irretrievable.
When hard disk drives get wet then dry out, there is nearly always a residue of contaminant left on the platters and heads. Any residue (including a piece of dust), causes physical degradation of the hard disk's platters and loses more data. 3 - DO keep the hard disk WET. Ideally, keep the hard disk drive in a sealed container to keep the hard disk drive wet. This stops the hard disk drive corroding and allows the technical staff at the recovery company to clean and dry the platters correctly with minimum damage to the platter surfaces.
Normally, Disklabs Data Recovery charges a premium for water damaged hard disk drives, however, this additional charge for the cleaning and drying out of the hard disk drive has been waivered for the victims of the latest flooding events.