MONA LISA (Marine and Onshore North Sea Acquisition for Lithospheric Seismic Analysis) seismic data was acquired by BIRPS (the British Institutions Reflection Profiling Syndicate) across the Ringkobing-Fyn High of the central North Sea were designed to study the crust near a hypothesized Caledonian age triple junction associated with the colliding continental crust of Laurentia, Avalonia (Gondwanaland) and Baltica. The specific target was the eastward continuation of the Caledonian Front (Iapetus Suture), as previously recognised on NEC (North East Coast line), MOBIL (Measurements over Basins to Image Lithosphere), NSDP (North Sea Deep Profile) and BABEL (Baltic and Bothnian Echoes from the Lithosphere) profiles, in northern Europe. 1112 km of data were acquired, recorded to 26 s two-way time.