The ESA’s geomagnetic field mission, Swarm is composed of three satellites equipped identically with the Absolute Scalar Magnetometer (ASM), Vector Field Magnetometer (VFM), Langmuir Probe (LP), Thermal Ion Imager (TII), and Accelerometer. The three satellites were launched into the same altitudes (~500 km) with an orbit inclination angle of 87.3o. During the first two months the satellites were flying in a pearls-on-a-string configuration. Between February and April 2014 the spacecraft conducted orbit maneuver. Since 17 April 2014 the lower satellites, Swarm-Alpha and Swarm-Charlie have been flying side-by-side at altitudes around 470 km. The upper satellite, Swarm-Bravo flies higher by about 50 km, with the orbital plane being separated gradually from that of the lower satellite pair. Observation of ionospheric irregularities by the multiple Swarm satellites can help elucidate 3-dimensional morphology of the ionospheric irregularities. Selected examples of plasma density irregularities observed by Swarm are described in detail and discussed during this presentation.