An explorable O'Neill cylinder you can walk around in
Island Three is a free, browser-based explorable 3D recreation of Gerard K. O'Neill's largest space settlement design — a pair of counter-rotating cylinders at the Earth–Moon L5 point — paired with an editorial timeline tracing the real and projected milestones from today's rockets to a completed colony in 2133.
A walkable virtual colony modeled on O'Neill's Island Three design (built slightly slimmer at 6.4 km across, versus the 8 km original): three valleys alternating with three windows, rotating about once every two minutes for Earth-normal gravity. Visitors can ride a scooter down valley avenues or tak
A second cylinder 40 km away, spinning the opposite way and joined by girders beyond the end caps, with mirrors that mesh like gears. Its valleys are visible through the windows, and both hulls and mirror backs are plated and lit only by the Sun.
The three great mirrors actually reflect — showing the hull, the other valleys through the windows, the sister cylinder, and only past that, the stars. Stars sit where they really would at the Earth–Moon L5 point, with the Milky Way crossing the windows at a slant, and Earth (a gibbous blue marble n
Each valley has a 56,000-seat football stadium at real dimensions — a 105 × 68 m pitch with full markings, two tiers of seating at real angles, glazed boxes, a floating roof trimmed in brass, and Art Deco floodlight towers — with Arden Valley getting two.
At dusk the mirrors fold and the far valleys appear overhead as fields of light.
A detailed chronology in four phases: what already happened (1975 NASA/Stanford summer study, The High Frontier, reusable boosters, Artemis, Moon Base plans through 2133), official targets (Starship orbit, Blue Moon landings, Chang'e 7, ISS retirement), projected industry beyond Earth (2033–2062: lu
The first visit builds the whole world, which the site notes may take a minute.
Visitors click through from the homepage into the 3D world, where the entire environment is generated on first visit. From there they explore on foot, by scooter, or by elevated train, and can look up to see the far side of the cylinder overhead, the mirrors reflecting the colony, and Earth and the
No pricing is mentioned anywhere on the site; the experience is accessible directly at islandthree.world with no account or payment step indicated.
It's an explorable 3D web recreation of Gerard K. O'Neill's largest space settlement design — a pair of counter-rotating cylinders at the Earth–Moon L5 point — that you can walk around in, plus a timeline of real and projected milestones that could lead to such a colony.
Zach Kauble, who says he's been fascinated by the O'Neill cylinder since second grade after reading about it in Roy A. Gallant's Our Universe. Contact is provided as [email protected].
It follows O'Neill's published design closely — paired counter-rotating cylinders with three valleys and three windows, spinning about once every two minutes — though the built version is deliberately a little slimmer at 6.4 km across versus the original 8 km.
Explore on foot, ride a scooter down valley avenues, take an elevated train to the hillside terminus, watch the dusk sequence when the mirrors fold, look up at the reflected colony and stars, and find Earth and the Moon through the windows.
The site mentions no pricing, accounts, or payments — you simply enter the colony from the homepage.
It's organized into phases: events that already happened through 2026, scheduled official targets (with a note that they often slip), and author-projected milestones from ~2033 through Island Three's first residents in 2133 — the projections are the author's estimates, not anyone's official schedule.
The site's projection puts construction starting around 2110, the shell closed and spun to 1 g around 2125, and first residents arriving in 2133 — contingent on projected milestones like cheap heavy lift, lunar industry, a mass driver, and an L5 construction yard.
