Alien Submarine

Lore & Background

The alien armada that besieged Earth did not arrive solely from the sky. Their fleet included heavy aquatic platforms—submarine-class vessels designed to operate in oceans, lakes, and flooded coastal zones. The Alien Submarine is one such platform: a bulbous, bio-mechanical hull bristling with weapon emplacements, propulsion thrusters, and secondary launch bays for smaller drone units. Its design blends the organic, chitinous aesthetic of the alien infantry with the industrial bulk of a warship, giving it an unmistakable silhouette against the waterline.

In the context of the invasion, these vessels served as mobile command and bombardment nodes. While the main alien mothership and ground installations handled the bulk of the assault, the submarines provided flanking pressure along coastlines and in inland waterways, making it impossible for any single defensive position to ignore the water. Sam's encounters with them typically come after he has already thinned the surrounding infantry, forcing a focused duel against a target that is slow but heavily armored.

Across the series, the submarine's role has remained consistent: a heavy, methodical threat that rewards patience and the right weapon choice over raw speed. It is not the final boss, but it is the kind of enemy that, if ignored, will chew through lighter defenses and reposition to threaten the next objective.

In Their Own Story

The lake was calm. Too calm. Sam wiped the spray from his visor and checked the ammo counter on his rocket launcher, watching the number tick down with every salvaged crate. Then the water bulged. A ridge of dark, ridged hull broke the surface thirty meters out, trailing a wake of churned silt. The Alien Submarine rose slowly, its weapon ports grinding open with a wet, mechanical shriek, and a volley of plasma bolts stitched across the shore where he'd been standing a second ago. He dropped behind a concrete pillar, reloaded, and grinned. The thing was slow. He had time.

Reader's Guide

Visual identity and role: The Alien Submarine reads as a large, low-slung armored hull—think a bio-mechanical torpedo or a squat warship—sitting half-submerged in water. It is the heaviest non-boss enemy in a water-based wave, anchoring the fight while smaller drones and infantry circle it. Identify it by its size, its thruster glow, and the secondary launch bays on its flanks.

Attack pattern: It fires broad, slow plasma or projectile volleys in a wide arc, giving you time to sidestep. Periodically it opens a side bay and ejects a small drone or torpedo that travels in a straight line—dodge laterally, not backward. It does not chase aggressively; it repositions slowly, so kiting is limited. Focus fire on exposed weapon emplacements or the hull's upper ridge where armor is thinner.

Where it appears: Water-based and coastal levels in the early Serious Sam titles. Expect it in the latter half of a water stage, after the initial infantry wave has been cleared.

Variants and upgrades: Later entries in the series may feature a larger or more armored variant with additional launch bays or a secondary turret. The core fight choreography—sidestep the volley, punish the reload window, destroy the side bays to stop drone spawns—remains consistent. A rocket launcher or heavy machine gun is the most reliable counter; shotguns and light pistols will take an impractically long time to break its hull.

Did You Know?

• The Alien Submarine's design language—organic chitin fused with industrial plating—mirrors the broader alien aesthetic used across the Serious Sam enemy roster, distinguishing it from human military hardware.
• Because it is slow and methodical, the submarine fight is often the one moment in a water level where Sam can afford to be deliberate rather than reactive, making it a tonal shift from the surrounding swarm combat.
• The submarine's secondary drone launches are designed to punish players who focus solely on the main hull, encouraging them to manage multiple threats simultaneously.
• Croteam's level design in the early titles often placed the submarine encounter after a sequence of lighter aquatic enemies, using it as a pacing breather before the next objective.