  We present the results of a multiwavelength study of the nearby dwarf galaxy
DDO 53 - a relatively isolated member of the M 81 group. We analyse the atomic
and ionised gas kinematics (based on the observations with Fabry-Perot
interferometer in H$\alpha$ line and archival data in HI 21 cm line),
distribution, excitation and oxygen abundance of the ionised gas (based on the
long-slit and integral-field spectroscopy and on imaging with narrow-band
filters), and their relation with the young massive stars (based on archival
HST data). We detect a faint 2-kpc sized supershell of ionised gas surrounding
the galaxy. Most probably, this structure represents a large-scale gas outflow,
however it could be also created by the ionising quanta leaking from
star-forming regions to the marginally detected atomic hydrogen surrounding the
galactic disc. We analyse the properties of the anomalous HI in the north part
of the galaxy and find that its peculiar kinematics is also traced by ionised
gas. We argue that this HI feature is related to the accreting gas cloud
captured from the intergalactic medium or remaining after the merger event
occurred >1 Gyr ago. The infalling gas produces shocks in the interstellar
medium and could support the star formation activity in the brightest region in
DDO 53.
