  Despite the important advances in space asteroseismology during the last
decade, the early phases of evolution of stars with masses above $\sim$15
M$_{\odot}$ have been only vaguely explored up to now. Our goal is to detect,
analyze and interpret variability in the early-B type supergiant HD\,2905 using
long-term, ground based, high resolution spectroscopy. We gather a total of
1141 high-resolution spectra covering some 2900 days. We complement these
observations with the $Hipparcos$ light curve, which includes 160 data points
obtained during a time span of $\sim$1200 days. We investigate spectroscopic
variability of up to 12 diagnostic lines by using the zero and first moments of
the line profiles. We perform a frequency analysis of both the spectroscopic
and photometric dataset. HD\,2905 is a spectroscopic variable with peak-to-peak
amplitudes in the zero and first moments of the photospheric lines of up to
15\% and 30 \kms, respectively. The amplitude of the line-profile variability
is correlated with the line formation depth in the photosphere and wind. All
investigated lines present complex temporal behavior indicative of
multi-periodic variability with timescales of a few days to several weeks. The
Scargle periodograms of the {\it Hipparcos\} light curve and the first moment
of purely photospheric lines reveal a low-frequency amplitude excess and a
clear dominant frequency at $\sim$0.37 d$^{-1}$. In the spectroscopy, several
additional frequencies are present in the range 0.1 - 0.4 d$^{-1}$. These may
be associated with heat-driven gravity modes, convectively-driven gravity
waves, or sub-surface convective motions. Additional frequencies are detected
below 0.1 d$^{-1}$. In the particular case of H$\alpha$, these are produced by
rotational modulation of a non-spherically symmetric stellar wind.
