https://en.wikipedia.org/wiki/Island_of_stability

This market defines the island of stability as any isotope from 109 - 115 protons and 173 - 187 neutrons. (This definition is open to revisions if I'm convinced that another definition would better fit the concept as it is known in 2024. An element's inclusion will not be revised after its half-life has been experimentally confirmed.)

The true half-life will be rounded to the nearest available answer on a log scale.

This market resolves once all isotopes in the island of stability have been synthesized and their half-lives tested, or their half-life has been computationally confirmed with near certainty, or it has been proven that the isotope is impossible to create.