No special access issues
The base of the boulder is often partially submerged.
It is possible to check the water level observations in Kunda here
https://www.ilmateenistus.ee/meri/vaatlusandmed/kunda/?lang=en
and forecast here
https://www.ilmateenistus.ee/meri/mereprognoosid/sea-level/?lang=en#layers/sea_level_longforecast
Kunda EH2000 water level roughly corresponds to
20 cm - water on all sides of the boulder
10 cm - the southern side is dry
-40 cm - the whole boulder is dry (has happened but is very rare)
Alternatively, it is possible to climb in the winter when the sea is frozen or by dealing with the shallow water is some other way.