  The observation of a wave group persisting for more than 200 periods in the
direct numerical simulation of nonlinear unidirectional irregular water waves
in deep water is discussed. The simulation conditions are characterized by
parameters realistic for broad-banded waves in the sea. The group is identified
by the solution of the associated scattering problem for the nonlinear
Schr\"odinger equation as the intense envelope soliton with remarkably stable
parameters. Most of extreme waves occur on top of this group, resulting in
higher and longer rogue wave events.
