Irradiating metallic nanostructures by an ultrafast laser beam produces highly localised processes on the nanoscale in the surrounding medium. This particular process is mainly attributed to the surface plasmon resonance of the nanostructures. When these nanomaterials are colloidal nanoparticles, their irradiation by an ultrafast laser could results in a highly localized plasma, heat production, pressure wave in the liquid and finally nanocavitation around the nanoparticles (1-5) . In this invited talk, I will cover recent developments of fundamentals aspects describing multiscale processes on the nanoscale as well as on ultrashort time (femtosecond to nanosecond). Multiphysics models based on electromagnetism, two-temperature model, thermodynamics and fluid dynamics have been developed to describe theoretically the productions of nanoplasma, pressure waves and nanocavitation. Models were successfully compared with experiments including shadowgraphy showing nanobubble dynamics and an all-optical pump-probe technique enabling the detection of plasmonic enhanced nanocavitation and pressure wave generation. Applications are in nanomedicine (6-7) in which ultrafast laser irradiation of these nanoparticles located close to a living cell, can produce a nanosurgery, can stimulate neurons or induce drug delivery. (1) E. Boulais et al, Nanoletters, 12, 4763-4769 (2012); (2) E. Boulais et al, Journal of Photochemistry and Photobiology C, 17, 26-49 (2013); (3) R. Lachaine et al ACS Photonics, 1, 331-336 (2014); (4) A. Dagallier, et al Nanoscale 9 (9), 3023-3032, (2017); (5) V. T. De Lille et al, to be submitted (2018); (6) E. Bergeron et al, Nanoscale, 7, 17836-17847 (2015); (7) F. Lavoie-Cardinal et al Scientific Reports, 6, 20619 (2016).