read the tittle its my question

Head to the northeastern-most corner of the map after Ishad N'ha (with Shurugeon Castle and Dragonspire), and you should find it. Look beyond the lake for a grassy mound; the entrance will be found on the north side, IIRC.

If that doesn't work for you just go straight across the lake when you leave Ishad N'ha. Be ready to be there for a while.

to back up bungleau's directions to the boogre cave, the lake is to the east of torin the samurai, follow the northern side of the lake n go onto the shore that is the very end. you should see a mound in the ground as kev stated...

Or just look for an "L" here.

how could you not finish boogre prison (or cave)???!!! the boogre withces in there always have a good chance of dropping an ankh after you kill them, and there is a HUGE and easy scorpion inside that will gif you around 10000 xp when u defeat it. there are also many treasure chests in that area which contain ankhs n the boogre cave is the path to another area on the map, not accesible by any other way, ONLY when you go through the boogre cave.
mind you, not finishing the boogre cave is a BIG loss for u. a monster in the new area of the map has an EXTREMELY important item that i myself would not leave it behind (read the magical lamp thingy that is somewhere in this website).
i recommend u to go back and complete the boogre cave.........

All that Plus the 'Idol of Bangu'...(a chance to get 'Giant Strike')

Besideds that....It's got the only bar in the Gael Serran, that actually sells beverages...instead of gossip.

I'm going back to the Boogre cave myself. Maybe I'll see you in the Boogre bar.