It's not a coin.
There appears to be several versions of such items (for example, one that reads "300 years of St. Petersburg" and one that reads "St. Petersburg" only, like this one; different placement of the mintmark, different obverse; some actually have the composition mentioned as part of the design).
I found the following data for the 300 years one:
Composition 925 silver
Strike quality proof
Weight 33.63 grams
Diameter 41 mm
Mintmark SPMD
But I do not know if this one is the same, as there were smaller versions (6.73 grams, 23 mm) as well .
(and while the photo of the small one I found showed the mintmark in a different place, I cannot say whether there were small ones that looked exactly like this or not).
Anyway, the ship seems to be one of the symbols of the city.
There appears to be several versions of such items (for example, one that reads "300 years of St. Petersburg" and one that reads "St. Petersburg" only, like this one; different placement of the mintmark, different obverse; some actually have the composition mentioned as part of the design).
I found the following data for the 300 years one:
Composition 925 silver
Strike quality proof
Weight 33.63 grams
Diameter 41 mm
Mintmark SPMD
But I do not know if this one is the same, as there were smaller versions (6.73 grams, 23 mm) as well .
(and while the photo of the small one I found showed the mintmark in a different place, I cannot say whether there were small ones that looked exactly like this or not).
Anyway, the ship seems to be one of the symbols of the city.



















