Open-water fraction across the (F_⋆, p_N2, Topography) parameter grid. Color indicates the global fractional area that remains ice-free at equilibrium, with darker shades marking more extensive open-water regions. At low incident flux (1000–1400 W m⁻²) and surface pressures (2 bars for less), all simulations remain predominantly glaciated. At 1600 W m⁻² and above, atmospheres exceeding a few bars develop measurable open-water areas, marking the onset of transitional climates.