I have visited
10 Sea Life Aquariums in 4 countries. Each is essentially a 45-minute visit and in truth they are not very memorable zoo stops. However, generally speaking, the ones I've seen in Europe have been more expansive than the small American locations.
My visits:
Sea Life Arizona (2011)
Sea Life Minnesota (2014)
Sea Life Grapevine - Texas (2015)
Sea Life Carlsbad - California (2017)
Sea Life Michigan (2018)
Sea Life Scheveningen - Netherlands (2019) - Humboldt Penguins and Small-clawed Otters
Sea Life Blankenberge - Belgium (2019) - California Sea Lions, Humboldt Penguins and Small-clawed Otters
Sea Life Konigswinter - Germany (2019)
Sea Life Oberhausen - Germany (2019) - Small-clawed Otters
Sea Life Hannover - Germany (2019) - has a Tropical House
The aquarium tanks are generally modern, sleek, clean, and appealing for families with young children. The establishments are full of bright colours and are obviously popular because there are almost 50 of them worldwide. The downside is that admission prices are far too expensive and many of the buildings are very similar. So, if you happen to be a zoo nerd who visits hundreds of facilities, then the Sea Life aquariums can all blend together after a while.

It's nice to see a few exceptions, such as Hannover with its Tropical House and some of the Sea Life aquariums that have outdoor sections. Every single one I've been to has been very busy, and there is often a lot of signs about conservation of aquatic life, so they aren't as bad as many folks make them out to be.