A very intimate and hidden speakeasy bar on Wellington Street, just east of Portland Street. As others have mentioned, it's easy to miss, but it's directly adjacent (above) to Bar Marben.
The Cloak Bar is super popular and gets quite packed during peak hours, so make a reservation on OpenTable or show up early. We showed up on a Saturday night without reservations and ended waiting 2 hours, hanging out at another bar, before getting in.
The bar is visually appealing with nice dim lighting, marble bar countertop and plentiful crystalware. The bar stool seating with the wooden tables, were a little more basic, but served its purpose.
The drink menu was extensive but intuitive and the service was friendly. I really enjoyed my pear, whiskey and egg white drink, although I forgot the name of it already (it was quite strong). Anyways, a super intimate bar that's good for a date night (as long as you don't mind moderate noise level).