Southern forts are easily accessible winter by the foot on the ice of gulf of Finland. For the experienced, well equipped and physical healthy local lore explorer it will not be a hard trip (but if you are not healthy and not well equipped - give it up).
First of all you need to reach Lomonosov city (former name Oranienbaum) or railway station Bronka. After that you should to get to the place named "Small Road of Life of Oranienbaum beachhead" (beginning of southern parts of the Dike). There is the unfinished concrete overpass over the road to Izhora city. Further you should come out on the ice of Gulf (see the Plan).