This is the list of all official events launched by the game staff.
On these occasions, qualified players gain access to special maps, which usually pertain to specific World War 2 battles. One exception is a tie-in to the anime Aoki Hagane no Arpeggio: Ars Nova. These maps are only available for the duration of the event (usually 2 weeks) and have better drop rates than normal sortie maps.
While sortieing in specific event maps, special Abyssal Fleet bosses may be encountered on predefined nodes. Although these event-limited enemies are strong, recurring bosses such as the Battleship Princess could also drain an admiral's bucket reserves.
Starting Spring 2014 event, LoS 
-based checks were implemented. A fleet's total or equipment LoS affects movement through the map nodes and whether you reach the boss node. Since then, this mechanic has been implemented into extra operations maps.
Event List
Tips
- The standard requirements to participate in an Event 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.
- A stockpile of
resources & 
buckets. Experienced admirals may have suggestions.
- Common knowledge says that resources' natural regeneration will allow the completion of all event maps in the usual two-weeks window. However, it depends on the mercy of the RNG for the fleet's consumption, damage dealt and received, paths taken, and the number of times required to clear an event map.
- Buckets do not naturally regenerate. It's highly recommended to stock up before the event.
- Although it's also a general rule-of-thumb, it deserves extra mention here: always have at least two of each ship type ready & leveled as the event maps' fleet composition requirements will not be known beforehand.