  Observers in de Sitter space can only access the space up to their
cosmological horizon. Assuming thermal equilibrium, we use the quantum
Ryu-Takayanagi or island formula to compute the entanglement entropy between
the states inside the cosmological horizon and states outside, as a function of
time. We obtain a Page curve that is bound at a value corresponding to the
Gibbons-Hawking entropy.
  At this transition an 'island' forms, which is in a significantly different
location as compared to when considering black hole horizons and even moves
back in time. These differences turn out to be essential for non-violation of
the no-cloning theorem in combination with entanglement wedge reconstruction.
This consideration furthermore introduces the need for a scrambling time, the
entropy dependence of which turns out to coincide with what is expected for
black holes.
  The model we employ has pure three-dimensional de Sitter space as a solution.
We dimensionally reduce to two dimensions in order to take into account
semi-classical effects. Nevertheless, we expect the aforementioned qualitative
features of the island to persist in higher dimensions.
