  The paper is devoted to the open problem of regularization by noise of 3D
Navier-Stokes equations. Opposite to several attempts made with additive noise
which remained inconclusive, we show here that a suitable multiplicative noise
of transport type has a regularizing effect. It is proven that stochastic
transport noise provides a bound on vorticity which gives well posedness, with
high probability. The result holds for sufficiently large noise intensity and
sufficiently high spectrum of the noise.
