Tom is having a relaxing day at the beach until Jerry appears on the scene to cause trouble for the poor puss. While trying to catch the cheeky mouse, Tom falls off a jetty and sinks to the bottom of the sea. Amazingly, he doesn't drown, and has fun mingling with the sea life, at least until pesky Jerry shows up again…as a mermouse! The first part of this T&J caper is pretty routine cat and mouse antics, but once the action takes to the seabed, things get a lot more entertaining, with loads of crazy shenanigans involving a variety of aquatic creatures, including a swordfish whose nose gets bent out of shape and an ornery octopus. Best visual gag of the whole cartoon involves Tom being hit on the head by an anchor with a massive rusty chain—the result is hilarious.Quite obviously, the underwater action turns out to be a dream for Tom, but the predictability of the ending doesn't spoil what is a very entertaining adventure for the troublesome cat and mouse.

It's very appropriate that this short was included on the disc for the Esther Williams film "Dangerous When Wet". This is because in this full-length film, Tom & Jerry appear in a fantasy sequence--swimming with Ms. Williams. So, seeing the pair frolicking about at the beach in "The Cat and the Mermouse" seems like a perfect extra for the disc.As I mentioned above, Tom & Jerry are at the beach. Not surprisingly, they begin beating the crap out of each other. Soon, Tom falls into the sea and sees Jerry...or what he thinks is Jerry. Instead, it's a 'mermouse'--a mermaid version of a mouse. For much of the rest of the film, it's like a standard Tom & Jerry cartoon but underwater. And, like in their appearance in "Dangerous When Wet", Tom doesn't seem to have any trouble breathing under water! Like any Tom & Jerry cartoon before they were ruined in the late 1950s (it's a long story but these later films were dreadful), the animation is top-notch--better than the Disney or Warner Brothers shorts. With wonderful backgrounds, great animations and lovely colors, it certainly looks great. As for the story, it's the usual but set in a very unusual locale--making it more enjoyable than an average film in the series. Not among their best, but quite good.

A typically intense chase for mouse blood on a beautiful sunny beach day ends up with Tom on the sea bed, where he finds the aquatic life amusing. He soon meets the mermaid version of Jerry and tangles with a scary swordfish, and a much scarier octopus!!! The animators really succeeded brilliantly in transferring the pair's usual havoc to an underwater setting. I love the beautifully detailed undersea backgrounds which are some of the best I've ever seen in anything that wasn't a Disney short. I also really liked the consistent animated small detail of the swirling bubbles that appear around the characters as they move. This particular short is packed with loads of really great little sight-gags, I love it when Tom mimics the turtle's leisurely swim, and the music that plays during that part is so funny and always stuck with me as a kid. And Jerry was wonderfully animated as well as being impossibly cute as the mermouse, his lower body replaced by a simply adorable little fishe's tale, on which he tiptoes on like two legs in a darling little comical moment! I also like the gag where he tries to sneak away from Tom by 'disguising' himself by swimming along in unison with a cadre of seahorses! The tug of war between Merjerry and the rather terrifying octopus that leads up to the big reveal of this short is is so surreal.. Just like in another classic Tom and Jerry short "Heavenly Puss", the entire show turns out to have been a dream, and like that one it also ends on the duo being nice to each other rather than their animosity, which, I always find really sweet and it rings true. And I always love the shorts like this one that take things in new and unexpected directions, pushing the boundaries of the show. I'd recommend this fine animation even if you're not a fan of these characters, as it's fantastic. Later!

While not a direct favourite of the Tom and Jerry canon, it is definitely worthwhile with some of the more funnier gags in the cartoons combined. The animation is really beautiful and creative and the music is as pretty much always a delight. The pacing is just right, and the story is original and works brilliantly. The sight gags are a great many but all of them work, the one with the swordfish was rather cruel for my liking but the ones with the octopus, the seahorses and any with the mer mouse worked superbly. I was surprised at how much was fitted in such a short running time, but overall, I just have to say bravissimo, for such an enjoyable and worthwhile Tom and Jerry cartoon. 9/10 Bethany Cox