That area seems to be under an Atlantic Gale Warning....Could be a rogue wave, although I’m a landlubber and don’t know anything about that type of water.
http://www.nhc.noaa.gov/text/MIAHSFAT2.shtml
Eh, the data taken literally shows the water column height rapidly oscillating wildly by 60 meters in the last three hours, preceded by almost no motion at all; really seems a malfunction is most likely.
The measuring device is actually on the sea floor; the buoy is just for communications. So it shouldn’t be triggered by storm waves.
http://www.ndbc.noaa.gov/dart/dart.shtml
DART® systems consist of an anchored seafloor bottom pressure recorder (BPR) and a companion moored surface buoy for real-time communications (Gonzalez et al., 1998). An acoustic link transmits data from the BPR on the seafloor to the surface buoy.
The BPR collects temperature and pressure at 15-second intervals. The pressure values are corrected for temperature effects and the pressure converted to an estimated sea-surface height (height of the ocean surface above the seafloor) by using a constant 670 mm/psia. The system has two data reporting modes, standard and event. The system operates routinely in standard mode, in which four spot values (of the 15-s data) at 15-minute intervals of the estimated sea surface height are reported at scheduled transmission times. When the internal detection software (Mofjeld) identifies an event, the system ceases standard mode reporting and begins event mode transmissions. In event mode, 15-second values are transmitted during the initial few minutes, followed by 1-minute averages. Event mode messages also contain the time of the initial occurrence of the event. The system returns to standard transmission after 4 hours of 1-minute real-time transmissions if no further events are detected.