  We investigate swampland conjectures for quantum gravity in the context of
M-theory compactified on Calabi-Yau threefolds which admit infinite sequences
of flops. Naively, the moduli space of such compactifications contains paths of
arbitrary geodesic length traversing an arbitrarily large number of K\"ahler
cones, along which the low-energy spectrum remains virtually unchanged. In
cases where the infinite chain of Calabi-Yau manifolds involves only a finite
number of isomorphism classes, the moduli space has an infinite discrete
symmetry which relates the isomorphic manifolds connected by flops. This is a
remnant of the 11D Poincare symmetry and consequently gauged, as it has to be
by the no-global symmetry conjecture. The apparent contradiction with the
swampland distance conjecture is hence resolved after dividing by this discrete
symmetry. If the flop sequence involves infinitely many non-isomorphic
manifolds, this resolution is no longer available. However, such a situation
cannot occur if the Kawamata-Morrison conjecture for Calabi-Yau threefolds is
true. Conversely, the swampland distance conjecture, when applied to infinite
flop chains, implies the Kawamata-Morrison conjecture under a plausible
assumption on the diameter of the K\"ahler cones.
