We took a trip to Colorado last May and despite staying close to Denver, we really didn't spend much time in the city. With just a couple of days to go before we flew home we thought we'd better do some intense sightseeing and set off into Denver to see as much as we could in just one day. Our final stop was a trip to the Downtown Aquarium. We'd done a bit of history at the State Capitol, had a hefty dose of culture at the Denver Art Museum and now we needed a seriously fishy experience to top off a great day out.

Challenge number one was to find the place. It's not obvious. Like a tantalus, the aquarium is something you can see from quite a distance but you just can't figure out how to get there until the penny drops and you realise the only way to get there is to go in the opposite direction. It took some time but we got there in the end. Pulling up in one of the massive car parks, we could see the Aquarium as a large round mirrored building.

Never mind the cost, let's see the fish. We entered and got diverted by a tank of beautiful bright green geckos and an old deep sea diving suit – of course we had to take our photos pretending to be old divers. Then we were into the fishy zone and thankfully there were very few people visiting that day so we could take our time.

So much, so cheesy. But it wasn't all bad. Because the place was so empty, we flitted back and forth around the aquarium – not something you can normally do when things are busy. There were two sea otters that were taking a nap and we went back every 15 minutes or so to see if they'd woken up but were disappointed that they never did. Perhaps they were stuffed, who knows. The point at which things really picked up was in the main central tank. For most aquaria this is the section you have to get right or you've blown it – pure and simple. The public will forgive you any misdemeanours; sleeping sea otters, jaded ducks, underactive seahorses and even (at a pinch) stuffed orang-utans are all forgivable if you get the big tank right. And generally speaking, Downtown Aquarium doesn't do a bad job at this. There's plenty of diversity in the big tanks, lots of sharks, lots of turtles, some giant moray eels and lots of different places to stop and look at them. However, whilst the big tanks is OK, the stars of the Downtown Aquarium aren't fish at all; the kings of the Downtown Aquarium are tigers.

We wandered off several times and kept coming back because one of the aquarium staff had told us that the tiger we'd seen didn't get on with the other tigers and once he went back inside, the others would probably come out to play. Eventually our patience paid off and we returned to find two large Sumatran tigers (the only breed that loves to swim) strolling around the larger enclosure, playing with the water toys and strutting around proudly. Whilst we weren't lucky enough to see the tigers swimming, there was a lot of time to watch video footage of them swimming and playing with toys in the water.

So is the Downtown Aquarium worth a visit? I'd say the answer to that lies more in the attitude of the visitor than in the aquarium itself. We could easily have been round the entire place in 30-40 minutes and back in the over-priced car park feeling let down and over-charged. It was only our determination to enjoy a slightly second-rate aquarium and to find the good in the place that made it such an enjoyable visit. That and the great attitude of the staff who infected us with their love of the animals they worked with which made us want to go back for a second or third look at some of the critters that hadn't been very interesting or very active at first sight.

The Downtown Aquarium has only traded under this name since 2003. Prior to that it was called the Ocean Journey Aquarium and I don't think it was doing very well. As a result it was bought by a chain of seafood restaurants called Landry's. Is it me or does that seem just a bit nasty? "Ladies and Gentlemen. Roll up and see the fish – then eat them"