  The environment of S187, a nearby H II region (1.4$\pm$0.3 kpc), is analyzed.
A surrounding shell has been studied in the H I line, molecular lines, and also
in infrared and radio continua. We report the first evidence of a clumpy HI
environment in its photodissociation region. A background radio galaxy enables
the estimation of the properties of cold atomic gas. The estimated atomic mass
fraction of the shell is $\sim$260~M$_{\odot}$, the median spin temperature is
$\sim$50~K, the shell size is $\sim$4 pc with typical wall width around 0.2 pc.
The atomic shell consists of $\sim$100 fragments. The fragment sizes correlate
with mass with a power-law index of 2.39-2.50. The S187 shell has a complex
kinematical structure, including the expanding quasi spherical layer, molecular
envelope, an atomic sub-bubble inside the shell and two dense cores (S187~SE
and S187~NE) at different stages of evolution. The atomic sub-bubble inside the
shell is young, contains a Class II young stellar object and OH maser in the
centre and the associated YSOs in the walls of the bubble. S187~SE and S187~NE
have similar masses ($\sim$1200~M$_\odot$ and $\sim$900~M$_\odot$,
respectively). S187~SE is embedded into the atomic shell and has a number of
associated objects including high mass protostars, outflows, maser sources and
other indicators of ongoing star formation. No YSOs inside S187~NE were
detected, but indications of compression and heating by the H II region exist.
