“Leviathan” can mean a few different things, and its size depends completely on which one you’re asking about.

Quick Scoop

If you mean:

  • Subnautica leviathans (video game)
    • Reaper Leviathan: about 55 meters long.
* Ghost Leviathan (adult): about 110 meters.

* Sea Dragon Leviathan: about 112 meters.

* Sea Emperor Leviathan: roughly 160–200 meters long.

* Frozen Leviathan (Below Zero): about 70 meters without the tail, around 150 meters total length.
  • Gargantuan Leviathan (fan / extended Subnautica discussions)
    • Estimates from fans and community wikis put it roughly in the 1,100–1,300 meter range based on fossil interpretations, with some threads throwing around even larger speculative numbers.
  • Mythical / biblical Leviathan
    • Ancient texts describe it as an enormous sea monster but give no precise measurement.
    • Modern fan discussions sometimes exaggerate it to hundreds of miles long (for example, a claim of “300 miles long” appears in a megalophobia discussion thread), but that’s symbolic and not a scientific figure.

Why the size is so confusing

“Leviathan” isn’t a single standardized creature; it’s:

  • A class of huge creatures in Subnautica, each with its own official length.
  • A fossil-based and heavily debated giant (Gargantuan Leviathan) where people extrapolate size from partial remains.
  • A mythological beast in religious and folkloric texts, meant more as a symbol of overwhelming power than a measurable animal, so later numbers like “300 miles” are interpretive or sensational rather than canonical.

Quick HTML table of notable “Leviathans”

html

<table>
  <thead>
    <tr>
      <th>Leviathan type</th>
      <th>Approx. size</th>
      <th>Source / context</th>
    </tr>
  </thead>
  <tbody>
    <tr>
      <td>Reaper Leviathan</td>
      <td>~55 meters long [web:1]</td>
      <td>Subnautica in-game data and wiki [web:1]</td>
    </tr>
    <tr>
      <td>Ghost Leviathan (adult)</td>
      <td>~110 meters long [web:1]</td>
      <td>Subnautica in-game data and wiki [web:1]</td>
    </tr>
    <tr>
      <td>Sea Dragon Leviathan</td>
      <td>~112 meters long [web:1]</td>
      <td>Subnautica in-game data and wiki [web:1]</td>
    </tr>
    <tr>
      <td>Sea Emperor Leviathan</td>
      <td>~160–200 meters long [web:1]</td>
      <td>Subnautica in-game data and wiki [web:1]</td>
    </tr>
    <tr>
      <td>Frozen Leviathan</td>
      <td>~70 m without tail, ~150 m total [web:1]</td>
      <td>Subnautica: Below Zero data and wiki [web:1]</td>
    </tr>
    <tr>
      <td>Gargantuan Leviathan (fossil)</td>
      <td>~1,100–1,300 meters (fan extrapolation) [web:3][web:5]</td>
      <td>Community debates and fan calculations [web:3][web:5]</td>
    </tr>
    <tr>
      <td>Mythical/biblical Leviathan</td>
      <td>Sometimes claimed as “hundreds of miles,” e.g., 300 miles in one discussion [web:10]</td>
      <td>Symbolic descriptions, later speculative numbers [web:10]</td>
    </tr>
  </tbody>
</table>

Forum-style takeaway

In games like Subnautica, “Leviathan” usually means tens to a couple hundred meters long. In myths and some modern forum posts, people blow it up to absurd, symbolic sizes—like hundreds of miles—so the “real” size totally depends on which Leviathan you’re talking about.

TL;DR:

  • Subnautica leviathans: roughly 50–200 meters, with one fossil-based giant estimated over a kilometer.
  • Mythical Leviathan: no fixed size, sometimes hyped up to hundreds of miles in modern discussion, but that’s symbolic rather than measured reality.

Information gathered from public forums or data available on the internet and portrayed here.