Or in Flemish, Café Botteltje is part of Hotel Marion near the seafront in Ostend. It gets it's name from it's stock of bottled Belgian beers and it has approximately 300 of them. It also has 13 on draft and 50 Belgian Gins, no that I drink shorts. There is Wifi too, which is free but you have to ask for password. It opens at 11:30 everyday apart from Mondays when it opens at 16:30.
Reviews of Cafe Bottle are aplenty on the Internet and all follow the same track. While they all praise the selection of beers, most bemoan the poor service that they got. On my visit, nothing could be further from the truth. The lady behind the bar, do they have barmaids in Flanders, was excellent. Nothing was too much trouble and her knowledge of local brews was outstanding. Below is what I worked my way through, all rather slowly as the ABVs were rather high.
My recommendation is just go there, you won't be disappointed. Oh yes, they do rather good food too.