The Baltic Sea Anomaly as a bunker or as a coastal defense structure


The Baltic Sea anomaly consists of 3 objects located close to each other. There are only sonar scans available for two of these objects.

The first object is the main object and publicly the best known. The second object is about 200 meters (656 ft.) away and has a diameter of 40 meters (130 ft.) and has more or less the same outline. There is very little known about this second object and no detailed sonar scans have been released. It is quite possible that the objects were joined together as two components of a larger structure.

The depth of the corridors on the main object is about 1,5 meters, which is not enough height for a normal human-sized passage. However, if the two objects fit together having the same corridors and spaces left out, then the combined height would be 3 meters, which is a comon height often used for corridors and rooms.

Dennis Åsberg of the Oceans X team commented that there are many indications that the objects seem to be part of a man-made building.

Both objects could have fitted together sitting on top of each other. In that case, we may be looking at a construction or building made out of large components. The weight and size of these objects are massive and must have made it very difficult to transport and prone to accidents. Component-based construction makes a lot of sense when using small to medium sized components. Beyond a certain size and weight, it becomes a very challenging task to transport and assemble.



Airfix - coastal defence fort
The Airfix 1/72 coastal defence fort from the Airfix Tribute forum



The preferred way for building, in general, is to do all the work at the final destination. Small to medium-sized components like walls are often pre-fabricated and then transported and assembled on site. The size of these components is limited by transport and technical know-how. Large constructions need tons of materials and a team of experienced builders.  Large components as  the Baltic Sea Anomaly would create unimaginable challenges. It would be hard to construct in one location and then transport to the final destination where it will need to be assembled. You would need a sizable team of engineers and specialized equipment for these complicated tasks. If we are indeed looking at a construction consisting of multiple components then it is more likely that there was an accident during transport. This would place the structure in a far more recent time period.

The only reason, I can think of, for justifying working with a component that has a 60-meter diameter, is if it would be related to a secret military operation. The military employs its own engineers but does not normally employ its own builders. It is usual that the military uses civil contractors for construction work. If the construction and its location would need any form of secrecy it would make sense to create the components in a factory far away before shipping it out to its final location where military engineers can mount and assemble the components in a record time. Military personnel is bound to secrecy while civil contractors are more difficult to control.




The Baltic Sea Anomaly as the ceiling of a bunker


My first impression looking at the Baltic Sea Anomaly is that it resembles the upside-down roof of a 19th or 20th-century bunker and we are looking at the underside of the ceiling. It is a structure similar to the ones used during the two world wars. At least 4 key features of the main object resemble those that can be found on bunkers still located all over Europe. The two objects could be part of the same round bunker as they have the same outlines and could possibly fit together as two halves of a cake. The corridors and rooms could be left out on both of the halves and when fitted together the height of each room is the sum of the spaces left out. The sizes of the rooms and corridors are not uncommon for bunkers and fortifications

At this time there is not enough information on the second object to verify if the corridors found in the first object are also spared out and that they are indeed matching.



The Baltic Sea Anomaly as a bunker

 The Baltic Sea Anomaly as the ceiling of a bunker or coastal fortification


There is a 3-meter wide dome located on the main object. It is not known if there is a matching hole in the second object. The two objects could have been designed as pre-cast concrete structures that are interlocking. In that case, the ball and hole could serve as a dowel joint to position and fit the two concrete slabs together.



Connecting the two Baltic Sea Anomaly objects together 

 The Baltic Sea Anomaly - fitting the two objects together



The round platform with the arched beam

An arch is a curved structure that spans an elevated space and may or may not support the weight above it. - Wikipedia

On the main Baltic Sea Anomaly object, there is a round structure with something that looks like a bent/arched beam. An arch is usually used to support the weight above it. Arches can take a lot of force but only in a single direction, a force applied in the opposite direction would break the arch. The bent beam in the platform indicates that the force needs to come from the other side of the platform. That would mean that the disk is lying upside down and we are looking at the bottom of the platform.

The platform has a diameter of 15-meters (49.2 ft.) and could have served as the base for a pillbox or air defense. Such defensive structures are common features on coastal fortifications.

Alternatively, the platform may have been located above a shaft as support for a lift mechanism. A shaft would indicate a deep underground military base (DUMB). I doubt that this would have been the case. A shaft leading to an underground base would have been the most important part of the structure. The role of the bunker would then have been to protect the access to this shaft. You would therefore expect the platform and shaft to be located in the middle of the bunker where it would have been best protected by the largest amount of reinforced concrete and not located on the outer edge, as is the case with the current design.



Baltic Sea Anomaly - measurements of the round platform
Type  Meters   Feet 
Diameter outer ring 15 49,2 
Diameter inner ring 13 42,7 
Width of arched bean 3 9,8 



The Baltic Sea Anomaly upside down

The Baltic Sea Anomaly shows features that are comon on bunkers and coastal fortifications 



The staircase – loophole for artillery

One of the key features of the Baltic Sea Anomaly is something that resembles a 14-meter wide staircase connecting to the outside. There are 7 steps, each having the same dimensions and each step showing a large drop. This drop from step to step is too much for a staircase but would be in line with the type of overhanging stacked ledges commonly found on WWII bunkers to protect artillery from shelling as can be still seen on historic bunkers all over Europe.



Protective layered ceiling for artillery 

 How the Baltic Sea Anomaly could have been the ceiling part of a bunker or coastal defense structure


The Baltic Sea Anomaly - Measurements of the artillery stand
Type  Meters   Feet 
Largest width 15 49,2 
Depth 14 45,9 
Number of steps - 7     
Width of each step 1 3,2 
Rise of each step 0,5 1,6 


Large defensive lookout post

This space is perfectly suited for defense, as it seems to have access to the outside and could have served as a large lookout. The ceiling width is almost 7 meter between the room and the outside and there is enough space for artillery.



The Baltic Sea Anomaly - the large loophole

 The Baltc Sea Anomaly shows feature that could possibly be features of a bunker or a coastal defense fortification



Ammunition depots

Behind the place with the “stairs” there are to two large rooms connected by corridors. One room is close to the entrance and could have been used to store ammunition for immediate use. The second room is further away and could have been used as a backup.



Key features on the Baltic Sea Anomaly

- that could posibly indicate we are looking at the underside of the ceiling of a bunker





A floorplan from the Baltic Sea Anomaly