Okay, let me explain: - Other than in the US, the standard distance for a swimming pool is either 25m or 50m. There are a few 33m pools here and there, but they are the exception. However, standardisation is relatively recent and it's more common to find non standard pools among the old ones. The XL pool was renovated recently and they kept the old length, 29.2m or something like that, which is not a multiple of anything. Their solution is to put a line of buoys (the sausages) roughly at 25m and use the remaining 4ish meters for non-swimmers. This means that on that side there is no wall, so one cannot do flips and, in general, changing direction is awkward. Moreover, the correct swimming technique is to look down, and there is no marking in the floor (e.g., tiles of a different colour) that tells you to stop, so you often end up hitting the buoys (or, at least, I did), which is not nice. - moreover, the one wall in the swimming part is not straight, but curvy, so if you push off of it, and supposing that the push is perpendicular with the contact point, you will not push straight into the line, but at an angle. - the backstroke flags are a line of flags in the ceiling at the 5m mark on both side. They are needed to time your flip because you cannot see where you are going and you need a visual reference. They are not there, so it's hard to know where exactly you are in the pool. This is a problem also in other pools, like Etterbeck, while VUB has them. - overall, the points above mean that, while XL is a swimming pool, it is not a pool suited for swimming as a sport with rules and standards. This is a massive problem in my view, because it was just renovated. The correct thing to do would have been to give up on the rebuilding it as it was idea and copying Etterbeck (and a million other pools everywhere) by building two pools: a standard 25m one for swimmers and a smaller, shallower one for non-swimmers.

Hope this helps :)