  Rogue waves (RWs) can form on the ocean surface due to quasi-four wave
resonant interaction or superposition principle. Both mechanisms have been
acutely studied. The first of the two is known as the nonlinear focusing
mechanism and leads to an increased probability of rogue waves when wave
conditions are favourable, i.e., when unidirectionality and high narrowband
energy of the wave field are satisfied. This work delves into the dynamics of
extreme wave focusing in crossing seas, revealing a distinct type of nonlinear
RWs, characterized by a decisive longevity compared to those generated by the
dispersive focusing mechanism. In fact, through fully nonlinear hydrodynamic
numerical simulations, we show that the interactions between two crossing
unidirectional wave beams can trigger fully localized and robust development of
RWs. These coherent structures, characterized by a typical spectral broadening
then spreading in the form of dual bimodality and recurrent wave group
focusing, not only defy the weakening expectation of quasi-four wave resonant
interaction in directionally spread wave fields, but also differ from classical
focusing mechanisms already mentioned. This has been determined following a
rigorous lifespan-based statistical analysis of extreme wave events in our
fully nonlinear simulations. Utilizing the coupled nonlinear Schr\"odinger
framework, we also show that such intrinsic focusing dynamics can also be
captured by weakly nonlinear wave evolution equations. This opens new research
avenues for further explorations of these complex and intriguing wave phenomena
in hydrodynamics as well as other nonlinear and dispersive multi-wave systems.
