  We study the optical properties of MoS$_2$ nanotubes (NTs) with walls
comprising dozens of monolayers. We reveal strong peaks in
micro-photoluminescence ($\mu$-PL) spectra when detecting the light polarized
along the NT axis. We develop a model describing the optical properties of the
nanotubes acting as optical resonators which support the quantization of
whispering gallery modes inside the NT wall. The experimental observation of
the resonances in $\mu$-PL allows one to use them as a contactless method of
the estimation of the wall width. Our findings open a way to use such NTs as
polarization-sensitive components of nanophotonic devices.
