Saturation Diving Submarine Bay Guide

Submarines are the lifeline between your diver and the surface in Saturation Diving. Each class ships with a different hull capacity, oxygen reserve, sonar range, and storage bay, and the meta diverges enough that choosing the wrong sub for your squad will bleed credits for the first ten runs. This guide walks through every sub class, the hull upgrade path, the slot layout, and the customization options that actually move the credit-per-run needle.

Sub Bay Layout

The sub bay is the lobby hub where every dive starts. From here you can:

• Switch sub class — pick between Scout, Hauler, Explorer, and Leviathan. Each class is a separate purchase and unlock.
• Upgrade hull tier — four tiers per class, starting at Mk I and topping out at Mk IV (S-tier).
• Customize slots — swap the default sonar, light, and storage modules for higher-tier variants.
• Refill oxygen and rebreathers — stock up before every dive; rebreathers add 4 minutes of safety margin each.
• Check the dispatch log — recent runs, surfaced ore counts, and any incidents (crew blackout, hull breach, aggro chain).

The sub bay is also where you repair the sub between dives. Repairs cost credits and scale with the severity of the damage — a Leviathan that took a Maw Crawler hit can cost up to 1,200 credits to repair, which is why hull upgrades matter more than most players realize.

Saturation Diving submarine tour — every sub class and customization

Scout Class

The Scout is the cheapest sub and the right pick for solo divers or two-person squads. It carries:

• 18 minutes baseline oxygen (matches a Twin Reserve tank).
• 4 gear slots (1 tank, 1 drill, 1 light, 1 sonar or helmet).
• 1 surface beacon — lets you mark a fast surface route from the deepest part of Twilight Reef.
• 0 storage bays — ore must be banked at the cargo bay on the surface between dives.

The Scout shines in Twilight Reef and the upper Mid Ridge. It cannot reach Black Mound because its pressure rating caps at 2.8 atm. Best hull upgrade path is Mk II → Mk III, which raises the pressure cap to 3.2 atm and unlocks the Scout-Mk III that can support a single solo run into deep Mid Ridge.

Hauler Class

The Hauler is the workhorse of the fleet. It carries:

• 22 minutes baseline oxygen.
• 4 gear slots plus 2 storage bays — you can mine a full Twilight Reef pipeline and bank the ore without surfacing mid-run.
• 1 surface beacon.
• 1 reinforced hull — takes one Maw Crawler hit without breaching.

The Hauler is the credit-efficient pick for Engineer-Salvager duos. The two storage bays let the duo split the ore — Engineer banks the rare ore, Salvager banks the salvage containers — without crossing paths mid-dive. Hull upgrade priority is Mk II → Mk IV if you plan to push Black Mound, because the Mk IV’s reinforced hull handles Abyssal Stalker patrols.

Explorer Class

The Explorer is the Captain-friendly class. It carries:

• 26 minutes baseline oxygen (Cryo Helix tier).
• 5 gear slots (adds a second sonar or a rebreather rack).
• 1 storage bay.
• 2 surface beacons — useful for marking the captain’s preferred return route and a backup route.
• Built-in Mk II sonar — saves you the early Mk I to Mk II sonar upgrade credit push.

The Explorer is the recommended sub for a full four-role squad. The longer oxygen reserve and second surface beacon make coordinated windows easier to call. Hull upgrade path: Mk II → Mk III is usually enough; Mk IV is overkill unless you run Leviathan-tier hadal content.

Leviathan Class

The Leviathan is the endgame sub. It carries:

• 34 minutes baseline oxygen (Cryo Helix plus).
• 6 gear slots (full loadout for a four-role squad).
• 3 storage bays — the only sub that can carry a full Abyssal Hollow run’s worth of ore.
• 3 surface beacons.
• Reinforced Mk IV hull — takes two Maw Crawler hits without breaching.
• Built-in Mk III sonar and Mk III light — replaces the Mk I and Mk II upgrade pushes for Captain builds.

The Leviathan is expensive (8,500 credits to unlock from scratch) but pays for itself the first time your squad runs a successful Black Mound boss clear. Best paired with the endgame trio gear loadout.

Hull Tier Comparison

Class	Mk I Pressure Cap	Mk IV Pressure Cap	Storage Bays	Slot Count
Scout	2.0 atm	3.2 atm	0	4
Hauler	2.4 atm	3.6 atm	2	4
Explorer	2.8 atm	4.0 atm	1	5
Leviathan	3.4 atm	5.0+ atm	3	6

Slot Layout Tips

The default slot layout is fine for early-game runs. After level 15, customize to your role:

• Captain: replace the Mk I sonar with the Pulse Array Mk II for ore reveal; keep the Mk I light for now.
• Engineer: keep the Mk I drill and add the Mk I sonar for entity pings; skip the second light slot.
• Spotter: replace the Mk I light with a Mk II light and add the Echo Tracker at level 30.
• Salvager: keep the Mk I tank and the Mk I drill; add a second storage bay if the sub supports it.

Surface Beacon Strategy

Surface beacons are the single most underrated tool in the sub bay. Place the first beacon at the entrance to your dive route, the second at the deepest node you plan to reach, and the third at the backup surface route. Most wipes happen because a squad surfaces at the wrong node and has to traverse three corridors with 5% oxygen. Beacons prevent that.

When To Upgrade The Sub

The credit-efficient upgrade path:

1. Twilight Reef (levels 1-10): skip sub upgrades. The Scout’s Mk I hull is enough. Spend credits on the gear loadout instead.
2. Mid Ridge (levels 10-25): upgrade to the Explorer-Mk II for the longer oxygen reserve. The extra slot pays for itself in three runs.
3. Black Mound (levels 25+): unlock the Hauler-Mk III for solo Salvager runs, then save for the Leviathan unlock.
4. Endgame (levels 40+): Leviathan-Mk IV with the reinforced hull and Mk III sonar.

Common Mistakes

• Buying the Leviathan too early — the unlock cost is 8,500 credits, which is half of a fresh save’s first S-tier loadout. Wait until you have the S-tier gear before buying the S-tier sub.
• Ignoring hull repairs — a damaged hull costs more credits to repair than to upgrade. Run repairs between every Black Mound dive.
• Forgetting the storage bay — if you are running a Hauler, fill both storage bays before surfacing. Empty bays mean you are paying sub upkeep for nothing.

Pair This Guide With The Tier List

The dive gear tier list ranks every sub module and hull upgrade. This guide is the how — the tier list is the what. Read them together before any major credit push, and check the updates tracker for rebalance notes that might shift the meta mid-cycle.