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Because it was operating fairly calmly on the surface, which strongly suggests that it was a diesel boat. Nuclear subs stay submerged after leaving port to help

Because it was operating fairly calmly on the surface, which strongly suggests that it was a diesel boat. Nuclear subs stay submerged after leaving port to help keep stealth. Diesel subs, on the other hand, have to either surface, or extend a snorkel, in order to pull in air to run the engines to recharge the batteries. The US, like the UK, and France has a pure-nuclear submarine fleet; the last American diesel boat was taken out of commission in the nineties. This leaves countries like Germany, whose boats have a distinctive profile that the photographed boat doesn't have, and Russia.

pge 12y ago
In your comment about Germany, are you referring to the Type 209? My data is very dated (1997), but at that point, there were a lot of German-made diesels owned by other nations (including Argentina in the Falklands War). They are/were the Ak-47 of submarines, and many were substantially upgraded with things like Stirling engines so they could remain submerged longer. Point being, if it is a diesel (and I agree with your assessment that it is), it would be difficult to tell visually what nation it comes from, because many older diesels (particularly the German ones but also other) have been sold off and ended up in the fleets of various other countries.
- Sanddancer 12y ago
  You've got a point, there. I was mostly trying to point out that pretty much everyone else in the general neighborhood is nuclear-only. It could potentially be a Venezuelan sub, but I wouldn't put them high on the list of countries willing to do a stunt like this.
  - pge 12y ago
    Former Eastern Bloc nations or Soviet republics? I agree with you that the intersection of countries still using diesels and countries that would be poking around Sweden is a small set - no obvious candidates, unless the rumors are true that Russia has been unable to keep their nuclear fleet operational and has reverted to diesels.

pge 12y ago

In your comment about Germany, are you referring to the Type 209? My data is very dated (1997), but at that point, there were a lot of German-made diesels owned by other nations (including Argentina in the Falklands War). They are/were the Ak-47 of submarines, and many were substantially upgraded with things like Stirling engines so they could remain submerged longer. Point being, if it is a diesel (and I agree with your assessment that it is), it would be difficult to tell visually what nation it comes from, because many older diesels (particularly the German ones but also other) have been sold off and ended up in the fleets of various other countries.

Sanddancer 12y ago
You've got a point, there. I was mostly trying to point out that pretty much everyone else in the general neighborhood is nuclear-only. It could potentially be a Venezuelan sub, but I wouldn't put them high on the list of countries willing to do a stunt like this.
- pge 12y ago
  Former Eastern Bloc nations or Soviet republics? I agree with you that the intersection of countries still using diesels and countries that would be poking around Sweden is a small set - no obvious candidates, unless the rumors are true that Russia has been unable to keep their nuclear fleet operational and has reverted to diesels.