  We realize higher-form symmetries in F-theory compactifications on
non-compact elliptically fibered Calabi-Yau manifolds. Central to this
endeavour is the topology of the boundary of the non-compact elliptic
fibration, as well as the explicit construction of relative 2-cycles in terms
of Lefschetz thimbles. We apply the analysis to a variety of elliptic
fibrations, including geometries where the discriminant of the elliptic
fibration intersects the boundary. We provide a concrete realization of the
1-form symmetry group by constructing the associated charged line operator from
the elliptic fibration. As an application we compute the symmetry topological
field theories in the case of elliptic three-folds, which correspond to mixed
anomalies in 5d and 6d theories.
