Alright fair enough.
As the group begin to climb the stairs, they turn to a slope, and oil comes pouring down, taking them back to the bottom. A few of the remaining pirates near the top laugh as they begin blocking the stairs with furniture.
We went through that same trap when storming the place. Pretty funny seeing it happen to you guys.
The admiral comes in, and thinks if these men made it up despite this trap they must have had a way. He examines the stairs and after a minute he notices some puncture marks in the slope.
They must have used some weapon or item to make holes in the slope, then climb up by using their weapons as holds. If we can climb to the 2nd highest floor we can get on stable ground and break through and fight them. Then we just need to climb the last floor and we can hopefully find Gale.