We review properties of ultraluminous X-ray sources (ULXs) isolated recently in external galaxies. We suggest that ULXs are supercritical accretion disks like that in SS433, but observed close to the disk axes. The SS433 funnel parameters where the relativistic jets formed are estimated. Emergent X-ray spectrum in the proposed model of the multicolor funnel (MCF) is calculated. Another critical idea comes from observations of nebulae around the ULXs. We present results of 3D-spectroscopy of nebulae of several ULXs with the 6-m Russian telescope. We found that the nebulae to be powered by their central black holes.<br />