| Event | Rerun | Synopsis | Medals | OST | Gallery | Trivia |
- This article is about the major event/Intermezzo. For the music, see Under Tides (music).
Under Tides (SV; not to be confused with Children of Ursus) is the twelfth major event, third Intermezzo, and the first Celebration event in Arknights.
Operations[]
Clear 1-10 to access the SV (Under Tides) operations.
| Deserted Salviento | SV-1 • SV-TR-1 • SV-2 • SV-3 • SV-4 • SV-5 • SV-6 • SV-7 • SV-ST-1 • SV-8 • SV-9 • SV-ST-2 |
|---|---|
| Choppy Ruin | SV-EX-1 • SV-EX-2 • SV-EX-3 • SV-EX-4 • SV-EX-5 • SV-EX-6 • SV-EX-7 • SV-EX-8 |
Choppy Ruin operations are available in the event's second week.
All SV (Under Tides) operations are worth 28 
.
Annihilation[]
Flooded Seashore is introduced as the new Rotating Mission in November 1, 2021.
From November 1, 2021 to November 29, 2021, all Hypothetical Targets (The Grand Knight Territory Outskirts, Frozen Abandoned City, and Abandoned Mine) are available.
Operators[]
The following Operators will gain 50% more Trust (except from Annihilation):
Headhunting[]
- Main article: Headhunting/Banners/Former/2021
The third Celebration limited headhunting banner, Deep Drown Lament, is featured.
- A single
Song of the Sea Headhunting Permit can be claimed once while the Deep Drown Lament banner is up. - Every day, the player can perform one headhunting pull for free at the Deep Drown Lament banner. These free pulls do not transfer over to the next day, so they must be used before the daily reset.
- Note: Skadi the Corrupting Heart will be added into the Celebration limited Operators' pool on Stultifera Navis.
Corrupted Iberian Record[]
All Deserted Salviento operations award 
Corrupted Iberian Record when cleared, with more being given when the player clears the operation for the first time. Choppy Ruin operations only awards Corrupted Iberian Records when cleared for the first time.
Corrupted Iberian Records can be exchanged for various items in Barter.
The best Deserted Salviento operations to farm Corrupted Iberian Records are SV-7, SV-8, and SV-9 due to their good 
Orirock Cluster, 
Crystalline Component, and 
Integrated Device drop rates, respectively.
Try to Survive[]
The Try to Survive rewards can be claimed until November 11, 2021.
| Mission | Reward | ||
|---|---|---|---|
| Clear SV-1. |  30 | ||
| Clear SV-2. | 30 | ||
| Clear SV-3. | 40 | ||
| Clear SV-4. | 40 | ||
| Clear SV-5. |
| ||
| Clear SV-5 with 3 stars. | 60 | ||
| Clear SV-6. | 60 | ||
| Clear SV-6 with 3 stars. |  | ||
| Clear SV-7. | 60 | ||
| Clear SV-7 with 3 stars. |  | ||
| Clear SV-8. | 80 | ||
| Clear SV-8 with 3 stars. |  | ||
| Clear SV-9. | 80 | ||
| Clear SV-9 with 3 stars. |  | ||
| Clear SV-EX-1. | 30 | ||
| Clear SV-EX-2. | 30 | ||
| Clear SV-EX-3. | 40 | ||
| Clear SV-EX-4. | 40 | ||
| Clear SV-EX-5. | 40 | ||
| Clear SV-EX-6. | 40 | ||
| Clear SV-EX-7. | 80 | ||
| Clear SV-EX-8. | 80 | ||
| Clear SV-EX-8's Challenge Mode. |  | ||
| Clear SV operations except SV-TR-1 15 times. | 40 | ||
| Clear SV operations except SV-TR-1 45 times. | 60 | ||
| Clear SV operations except SV-TR-1 85 times. | 80 |
Barter[]
To buy all items with limited stock from Barter, the player must spend 6340 
.
Try to Survive missions award 1080 while the first clear rewards of SV operations award 960 , thus requiring the player to farm 3900 from SV operations.
Barter is open until November 11, 2021.
| Ware | Price | Stock |
|---|---|---|
 1 |
250
|
1 |
1 |
300
|
1 |
1 |
350
|
1 |
1 |
400
|
1 |
1 |
450
|
1 |
 1 |
150
|
3 |
 1 |
100
|
5 |
 1 |
45
|
10 |
 1 |
40
|
10 |
 1 |
35
|
10 |
 |
70
|
1 |
 |
65
|
1 |
 |
40
|
1 |
 |
20
|
2 |
 1 |
13
|
10 |
 1 |
12
|
10 |
 5K |
7
|
100 |
 2 |
5
|
25 |
 2 |
3
|
50 |
 2 |
1
|
120 |
 1 |
4
|
25 |
 1 |
2
|
50 |
 1 |
4
|
25 |
 1 |
3
|
25 |
 1 |
3
|
25 |
 1 |
6
|
5 |
 10 |
2
|
200 |
20 |
1
|
Unlimited |
Login Event[]
During the event, login to the game for 10 days to claim the following rewards.
| Day 1 | 30K  2 | ||
|---|---|---|---|
| Day 2 | 30K  2 | ||
| Day 3 |  200  25 | ||
| Day 4 |  1 10 | ||
| Day 5 | 15 2 | ||
| Day 6 | 1  5 | ||
| Day 7 | 30K 200 | ||
| Day 8 |  1 2 | ||
| Day 9 | 1 15 | ||
| Day 10 |
|
Store[]
ID Info Update Card Packs added into the Packs Store.
The following packs are available in the Packs Store until November 18, 2021:
| Pack | Content | Price |
|---|---|---|
| Rhodes Island Headhunting Pack |  1  1 |
US$29.99 |
| Rhodes Island Resource Pack | 90 1 200K 4 30 50 20 50 |
US$49.99 |
- Note: Both packs can only be purchased once per account.
Outfits[]
The following outfits are available in the Outfit Store:
| New |
|---|
In addition, players who had purchased Skadi's Waverider WR04 outfit before the event will receive one 
Outfit Voucher (given as an in-game mail) due to the release of Skadi the Corrupting Heart.
Furniture[]
The Iberian Resort Town furniture theme is available; some of its parts are awarded from completing Try to Survive missions while others are available in Barter and Furniture Store.
Miscellaneous[]
Operator Record/Paradox Simulation[]
New Operator Records/Paradox Simulations are added for the following Operators:
| Operator | Operator Record(s) | Paradox Simulation |
|---|---|---|
| Extra Work | A Line for Three | |
| Unexpected Annoyance | Immovable as His Name | |
| A Song and a Blue Feather | Impregnable Illusion | |
| Ha! Through to the Front! | ||
| Scorching-Hot Assault! | Not added |
Cautus Valley Mining Area[]
During the event, the player will receive one mining operation every day, which can be used to receive 
Orundum from three different types of Originium deposits in Cautus Valley Mining Area, selected at random in each use:
| Deposit | Value |
|---|---|
| Originium Crude Ore | 300 
|
| Originium Ore | 400 ~ 1700
|
| Originium Vein | 1800
|
- The amount of Orundum received will only be shown after the mining operation is completed.
- If the mining operation does not reach an Originium Vein, the next mining operation(s) are more likely to reach it. If an Originium Vein was not reached by the end of the event, then the last mining operation is guaranteed to reach an Originium Vein.
- Unused mining operations do not transfer over to the next day, so they must be used before the daily reset.