  Jet substructure, defined by observables constructed from the distribution of
constituents within a jet, provides the versatility to tailor observables to
specific regions of QCD radiation phase space. This flexibility provides
exciting new opportunities to study jet quenching in heavy-ion collisions and
to ultimately help reveal the nature of the quark-gluon plasma. The ALICE
detector is particularly well-suited to jet substructure measurements in
heavy-ion collisions due to its high-precision tracking system. In these
proceedings, we report several new jet substructure measurements in Pb-Pb
collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV with ALICE. These include the
first fully corrected measurements of the groomed jet momentum splitting
fraction, $z_{\rm{g}}$, and the groomed jet radius, $\theta_{\rm{g}} \equiv
R_{\rm{g}}/R$, as well as $N$-subjettiness and the fragmentation distribution
of reclustered sub-jets. These measurements are compared to theoretical
calculations and provide new constraints on the physics underlying jet
quenching.
