During events, qualified players gain access to special a time-limited world with special maps, which usually reference historical operations; the only exception was a collaboration event with the Arpeggio franchise: Aoki Hagane no Arpeggio: Ars Nova. Event maps stay up for an indeterminate amount of time, usually measured in weeks, which grew as the game progressed to be anywhere between 2 and 8 weeks.
Event maps pose considerably higher challenge levels compared to normal maps, employing exclusive special Abyssal Fleet bosses and mechanics, such as the Combined Fleet.
Starting on Spring 2014 event, LoS 
-based checks were implemented. A fleet's total LoS affects movement through the map nodes and whether you reach the boss node. Since then, this mechanic has been implemented into many other maps, more prominently on World 2-5.
Current Event
| Fall 2021 Event - Return of the Naval District Saury Festival |
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Past Event List
The past events are listed bellow for reference.
| Spring 2013 Event - Break into the Enemy Anchorage! |
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| Summer 2013 Event - Southern Waters Assault Reconnaissance! |
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| Fall 2013 Event - Final Battle! Iron Bottom Straits! |
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| Christmas 2013 Event - Intercept! Fleet of Fog |
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| Spring 2014 Event - Recon planes, launching! |
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| Summer 2014 Event - Operation AL/MI |
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| Fall 2014 Event - Operation Kon |
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| Winter 2015 Event - Counter-attack! Assault on Truk Anchorage |
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| Spring 2015 Event - Order! Operation 11 |
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| Summer 2015 Event - Counterattack! The Second Operation SN |
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| Fall 2015 Event - Breakthrough! Maritime Transport Operation |
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| Winter 2016 Event - Sortie! Operation Rei-Go! |
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| Spring 2016 Event - Deployment! Land-based Aerial Division! |
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| Summer 2016 Event - Counterattack! The Second Battle off Malay Peninsula |
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| Fall 2016 Event - Announcement! The Third Fleet Operation Act |
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| Winter 2017 Event - Reconnaissance Force Emergency Deployment! Operation "Hikari" |
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| Spring 2017 Event - Sortie! Fifth Fleet To the North East! |
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| Summer 2017 Event - Crossing into the West Again! The European Rescue Operation! |
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| Fall 2017 Event - Showdown at Operation Shou-gou! Battle of Leyte Gulf (Part 1) |
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| Winter 2018 Event - Showdown at Operation Shou-Gou! Battle of Leyte Gulf (Part 2) |
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| Fall 2018 Event - Set Sail! Combined Fleet, to the West |
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| Winter 2019 Event - Interception! Operation Buin Defense |
| Interception! Operation Buin Defense |
| Spring 2019 Event - Commence Allied Relief! "The 2nd Hawaii Operation" |
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| Summer 2019 Event - European Counterattack Operation! Commence "Operation Shingle" |
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| Fall 2019 Event - Advance! The 2nd Southern Operation |
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| Hinamatsuri 2020 Mini-Event - Peach Festival! Offshore Waves |
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| Summer 2020 Event - Stop the Invasion! Island Defense Fortification Operation |
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| Fall 2020 Event - Escort! Fleet Transport Operation |
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| Spring 2021 Event - Clash! Night Battle off Lunga |
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| Summer 2021 Event - Reinforcement Transport Operation! Battle of the Mediterranean |
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Event Preparation
The requirements to sortie to event maps are:
- At least a 75% sortie win-rate. This is shown in the Fleet HQ Stats page.
- At least 5 free ship slots for new kanmusu to join before sortieing.
- At least 20 free equipment slots before sortieing.
- Some maps might require specific conditions, such as not using a specific ship type, or using a specific fleet type.
Stockpiling
- Accumulating a stockpile of resources (
) and Buckets(
) prior the event start or during the weeks that lead up to an event is extremely recommended.
- Using the softcap mechanic to your advantage might be benefic should the situation demand for it. For each resource under the softcap, it is generated up to 1440 for and 480 for , per day.
- For reference, expedition 5 being run non-stop will bring in a gross 3850 fuel and ammo, and 257 steel and bauxite per day.
- As buckets do not regen over time, focusing on stocking buckets might be preferrable on a higher priority. Expedition 2 might be preferred for it's very high efficiency and low maintenance.
- Fuel and ammo are the most used resources and also the most easily obtained resources through expedition. Steel is used in a much smaller scale in comparison, but is substantially harder to stockpile in a shorter period of time. Bauxite uses will vary depending on each particular map.
- Using the softcap mechanic to your advantage might be benefic should the situation demand for it. For each resource under the softcap, it is generated up to 1440 for
Event Mechanics
Ship Locking
Ship locking is a system that restricts to which maps a certain ship may be sortied. When a ship is sortied to an event map for the first time, it will have a tag applied to it. The Tag System prevents any fleet with ships that have a tag different from the one that the map accepts from sortieing to said map. In Easy and Casual difficulties, tags are still applied, but are not checked, meaning you may still sortie fleets with ships with different tags, however the map's tags will still be applied to ships without any. Ships that already tagged cannot lose it through any means. Furthermore, a map might accept any or multiple tags, and as well not issue any tags.
Difficulty
Exclusive to event maps, a difficulty can be selected. The difficulties are referred to as "classes". Classes go from D (丁) to A (甲), with the western standard for difficulty being Casual (丁), Easy (丙), Normal (乙) and Hard (甲). Difficulty changes the enemy compositions, routing rules and map rewards accordingly, as well as ship drops tables with both their rates and availability being affected.