There are all near to Kronstadt...
You should go to subway station "Chernaja Rechka" (Black River). From here you should take the minibus to Kronsdadt and go forward. The way to Kronsdatd lie through the dike, from which is the shortest way to the northern forts of Kronsdat. Alas, but the minibuses does not stop on the dam because police restrictions.
1-7. Northern literal forts ##1-7;
8. Fort Torleben;
9. Fort Obruchev;
10. Fort Shanz;
11. Fort Rif
A. Kotlin island
Best season fot the visits to the forts is winter. You can go by the foot in any direction if ice will be hard enough. GPS wont be extra thing it these trips. In other seasons (summer) the motor boats should be hired in Kronstadt or Sestrorezk (for Totleben fort visit).