Electronics and water don't usually mix, but when they do, the results can be impressive - see for example the 10 top-notch bits of kit we've rounded up below, covering everything from smartphones (and smartphone covers) to underwater jet ski contraptions.
Whether you want to liven up bath time, need a shiny new toy to take on your next beach holiday, or want to be able to capture perfect photographs and video clips from under the waves, we've got you covered. Just try not to scare the fish too much along the way.
Header image: Nikon
1. GoPro Hero4 Session
The cheapest GoPro in the current line-up isn't quite as capable in terms of video recording quality and frame rates, but it's still waterproof - and you don't need to buy any extra cases to keep the water out either.
GoPro says the Hero4 Session is waterproof to a depth of 10 metres, so it should be more than adequate for those underwater shots of coral and startled fish. The top-end GoPro can go as deep as 40 metres, meanwhile. [GoPro, £159.99/$199.99]
2. Olympus Tough TG-4
Regarded as one of the best waterproof cameras on sale at the moment, the 16MP Olympus Tough TG-4 can keep snapping away at depths of up to 50 metres without the need for any additional cases or housing on top.
Waterproofing is just one of the impressive aspects of the Tough TG-4: it's also capable of handling extreme weather conditions and pressure, and producing some very decent photographs at the end of it all. [Olympus, £279.99/$349]
3. Light & Motion GoBe S 500 Search
Need to see what you're doing down at the bottom of the sea? The GoBe S 500 has you covered, with a beam that's rated to a maximum of 500 lumens. Battery life is anything up to 18 hours at the lowest brightness setting.
You can of course use it on ground as well as underwater, but the chunky torch is waterproof up to a depth of 120 metres. The spot beam has been specially optimised for adverse conditions too. [Light & Motion, $170 (£120)]
4. Seabob F5 Underwater Scooter
As far as underwater gadgetry goes you can't get much better than the Seabob F5 - it's like a jet ski that works beneath the surface of the water, letting you zoom around to your heart's content with the fishes and startled swimmers.
You are probably going to have to spend a little while saving up for one, but the wait will be worth it. The F5 model weighs in at 29kg and uses an electric motor, and it can work at depths of up to 40 metres. [Seabob, €7,845+ (£6,190/$8,770)]
5. Samsung Galaxy S7
Samsung's latest and greatest flagship smartphone is fully waterproof as well as being incredibly good-looking and blazing fast - the specs say it can withstand 30 minutes of dunking at a depth of 1.5 metres (an IP68 rating).
The Edge variant has exactly the same IP68 rating so you don't have to worry if you should drop in in the sea. The only potential problem is you'll need to wait for them to dry off before you can charge them again. [Samsung, £569+/$799.99+]
6. LifeProof Fré Power
Maybe you don't want to buy a completely new smartphone to go swimming with, you just want something that's protect your existing one: and that's where these rather handy cases from LifeProof come in.
The case shown here is for the iPhone 6S but you can pick them up for Samsung phones as well. The Fré Power case shown here will keep your precious handset safe at a depth of up to 2 metres for an hour. [LifeProof, £109.99/$129.99]
7. Finis Duo
Want to take your tunes down with you to the depths? It isn't easy, but Finis has one solution in the form of the Duo, which uses bone conduction technology to beam the music right into your inner ear.
That means no earbuds getting lost and flailing behind you in the water. There's 4GB of internal memory on board the MP3 player and the manufacturer quotes a battery life of seven hours between charges. [Finis, $119.99 (£85)]
8. Cressi Traveller Divers Watch
The Apple Watch may look shiny and flash on your wrist, but it's not going to cut it at a depth of 200 metres like the Cressi Traveller can - so you're always going to know what time it is when you're deep beneath the ocean waves.
With a mineral glass face, a soft rubber strap, luminescent dots and markers, and a magnifier above the calendar date, this is one of many quality watches you can find specifically designed for use underwater. [Cressi, £99.95 ($141)]
9. Nikon Coolpix AW130
The AW130 is built for a rugged lifestyle and that includes underwater adventuring - the 16MP camera can keep going at depths of up to 30 metres and has a lens and zoom specifically optimised for underwater use.
There's no case required so you can just carry on using it as you normally would. The device is available in four different colours and also comes well protected against shocks, dust and cold temperatures. [Nikon, £279.99/$349.95]
10. Underwater Disco Lightshow
We can't talk about underwater gadgets without referencing this funky accessory from Firebox, which turns bath time into a psychedelic chill-out for just a few pounds (you need to buy the batteries separately though).
It is of course 100 percent waterproof and you get a choice of different patterns, from the subdued to the crazy, enabling you to set the appropriate mood. Much more modern and tech-savvy than candles around the bath. [Firebox, £7.99 ($11)]