Sea Prisoner / Deep Blue Sorrow Full Guide: Song of the Whale Arc, Anima Weakness, Drive a Car Through Nautili Tunnel to Trigger

Key answer: Sea Prisoner / Deep Blue Sorrow is the giant-whale Anomaly in the waters of the New Herland District, weak to Anima (no resistance). Trigger: drive a four-wheel car through the Nautili Tunnel (west to east) (motorcycle doesn’t work — the number-one wall). The charging horn can be parried for a long stun. Guaranteed first-clear Song of the Whale S-rank Arc (Plasma, Aurelia BiS). Blossom team BiS: Nanally + Esper Zero + Hathor + Fadia.

ℹ Note: The commission name is confirmed as “Deep Blue Sorrow.” The Boss’s Anima weakness ≠ the Song of the Whale Arc element (Plasma) — don’t mix them up.

A giant whale-shaped ocean Anomaly with a single horn on its brow — Sea Prisoner drops “Song of the Whale,” Aurelia’s best-in-slot Plasma S-rank Arc, but its trigger condition is one of the most-overlooked in the whole game. This article lays out the trigger, moves, parries, and Blossom team in one place.

1. What is Sea Prisoner

Item	Details
Boss name	Sea Prisoner / Deep Blue Sorrow
Anomaly commission name	Deep Blue Sorrow
Type	Major world Boss / Anomaly commission, four-star commission
Appearance theme	Giant whale-shaped ocean Anomaly with a single horn on its brow (the charging horn); ocean / imprisonment theme

Location: the waters of the New Herland District (in Hethereau City). After unlocking, the Boss’s permanent respawn point is east of Cape Square, and you can re-challenge it any time. The trigger location is the Nautili Tunnel (an undersea tunnel) connecting Bridge Crossings and the New Herland District.

2. Unlock / Trigger Conditions (the hardest part of this commission)

Hard requirements (consistent across all sources)

• ⚠️ You must be driving a four-wheel car — a motorcycle / scooter does NOT work, the blue Anomaly portal will not spawn (the most-overlooked mechanic in the entire game, the number-one wall)
• Route: teleport to the Wetheimer Tower in Bridge Crossings → drive into the Nautili Tunnel, heading toward New Herland (west to east)
• As you drive, a glowing blue spacetime portal + an “Anomalous Realm” prompt appears ahead → do NOT stop the car, keep driving → water-ripple VFX → an ice-field road surface → drive into the arena and the fight begins

Community trigger tips (try one, defer to in-game)

Detail	English community	Chinese community
Entry method	Reverse / back in, front of car facing east	Hug the left lane the whole way
Time of day	Mostly no limit mentioned	Only at night, around 20:00-04:00 (won’t trigger in daytime)

The confirmed core: four-wheel car + go through the Nautili Tunnel west to east + don’t stop when you see the blue portal. The three trigger tips are listed as “community-reported tricks; the actual in-game version is authoritative.”

Recommended level: Lv 38+, bringing a healer is advised.

3. Element & Weakness

• Weakness: Anima — use Anima-element characters to stagger efficiently and shred its HP fast
• Resistance: None listed

4. Move List (Complete)

Overall rhythm: it’s huge, its actions are on the slow side, and almost every move has a red-light warning. Core principle: dodge the red light, parry the charge.

Phase 1 (about 100%-70% HP)

Move	Counterplay
Diving slam / breaching wave	Watch the red light and dodge
Geyser	Move out of the way
Homing projectiles / water-ball barrage	Dodge roll
Aerial dive	Watch the red light and roll

Phase 2 (below 70% HP, the arena rains and the attacks get wilder)

Move	Counterplay
Geyser + whirlpool	A warning red circle appears on the ground; the moment it shows, move out immediately
Anchor	Throws a bright-red anchor in a straight line from above; can be parried / countered
Tsunami red waves	Multiple red tsunamis push forward; dodge only (i-frames of the roll)
Diving thrust / charge (signature)	Flies up then dives with the horn; can be parried → long stun

Parryable vs Dodge-only (key)

Move	Handling
Diving thrust / charging horn	✅ Parryable → triggers a long stun (very wide parry window; stay calm and wait for it to close in before blocking; the biggest damage window of the fight)
Anchor	✅ Parryable / counterable (use a Rail Counter / Ultimate / normal attack)
Tsunami red waves	❌ Dodge only (i-frames of the roll, do NOT run the opposite way)
Geyser / whirlpool (red circle)	❌ Move out of the circles only
Homing projectiles, dive	❌ Mainly dodge

Phase thresholds: the English mainstream uses a single 70% threshold; some Chinese guides use three phases (100-60% / 60-30% / enraged below 30%). Defer to in-game.

5. Drop Rewards

First-Clear Core: Song of the Whale

• Rarity / Element: S-rank Plasma Arc (⚠️ the Boss is weak to Anima, but this reward Arc is Plasma — don’t mix them up)
• Effect (“Deep Blue Sorrow”): ATK +12% (+24% at max level), +12% damage to staggered enemies, restores 30% HP when you defeat a staggered enemy (at most once every 30 seconds) — a hybrid attack + survival (lifesteal) type
• Best character: Aurelia — the signature pairing; she reliably drives enemies into the staggered state

For full Arc details, see the Aurelia Full Build Guide.

Other Drops / Commission Rewards

• Tear of the Sea — a quest-designated material (repeatably obtainable)
• Hunter EXP 300, Crystals 40, Fons 15,000, Silver Vine 80, U-00NE 30, Beetle Coins 7,500, Anomaly Material Selection Box I × 5
• Arcane Thread / Runic Thread

Weekly re-runs: the first clear grants Song of the Whale (one-time); after that, re-runs mainly produce materials (Tear of the Sea, threads, Beetle Coins, Hunter EXP). The exact weekly cap is authoritative in-game.

6. Recommended Teams (Anima Weakness)

GameWith Recommended “Blossom Team” ⭐

Nanally (Anima Main DPS) + Esper Zero (Cosmos) + Hathor (Lakshana) + Fadia (Survival / Healer)

Nanally Hypercarry

Nanally (Main DPS) + Skia (Sub-DPS) + Mint (Buffer) + Chiz

Hathor Charge Team

Hathor (Main DPS) + Jiuyuan / Mint (Sub-DPS) + Edgar (Buffer)

Team-building rule: prioritize Anima-element damage (Nanally, Jiuyuan) to exploit the weakness and stagger fast; pair with one healer / survival unit (Fadia / Sakiri) to handle the full-screen red circles, water explosions, and tsunamis in Phase 2.

7. Combat Tips + Common Beginner Mistakes

Reliable Triggering (most critical)

1. First make sure you have a four-wheel car (if not, go get / summon one)
2. Teleport to the Wetheimer Tower in Bridge Crossings, drive toward New Herland through the Nautili Tunnel (west to east)
3. (Community tips, try one) night 20:00-04:00 / hug the left lane / reverse in with the front of the car facing east
4. When you see the blue portal, do NOT stop the car — keep driving across the water → ice field → into the arena

Two-Phase Strategy

• Phase 1 (>70%): calmly watch the red light and dodge, focus-fire with Anima to stagger. Always parry the charging horn → one success buys a long weakened-state damage window (the biggest DPS in the fight)
• Phase 2 (below 70%): the arena rains and the rhythm gets chaotic. Move out of the ground red circles, eat the tsunamis with roll i-frames, counter the anchor with a Rail Counter / Ultimate / normal attack, and keep parrying the charge

Common Beginner Mistakes

❌ Mistake	Consequence
Riding a motorcycle / going on foot to trigger	The portal never appears (the number-one mistake)
Stopping / getting out when you see the portal	The trigger is interrupted — you must keep driving the whole way
Running the opposite way from a tsunami	You eat full damage instead; stay put and dodge with i-frames
Mindlessly dodging the charge	Wastes the biggest damage window from parry-stunning it
Giving Song of the Whale to an Anima character	The Boss is weak to Anima, but Song of the Whale is a Plasma Arc, best on Aurelia
Tanking the full-screen red circles without a healer	You die easily — bring Fadia / Sakiri

8. Related Guides

• Anomaly Boss Full Bestiary — overview of all 18 Bosses
• Serenetti / Mammon / Headless Rider / Beat King / Nestbound Bird / Black Tome / Arachne / Swallowtail / Morphix — other popular Bosses
• Aurelia Full Build Guide — Song of the Whale’s best owner
• Vehicles Full Guide — how to get a four-wheel car
• Elemental Reaction System — the Blossom reaction

FAQ

Sea Prisoner data compiled from public sources including Game8, GameWith, GameRant, GAMES.GG, ZeroLuck, AllThings.How, Sportskeeda, Nerdschalk, Icy Veins, Entertainment Taxi, LDPlayer, 4Gamers, and Bahamut. Trigger details (reversing vs night + left lane), the commission name, the phase thresholds (70% vs 60%/30%), and the weekly reward cap should follow in-game.