Swim workouts are serious business, and sometimes you need a little music to keep your energy up. Waterproof MP3 players let you take your favorite tunes to the pool, lakes or the ocean where the music can motivate, soothe, and keep your mind busy while your body is hard at work.

But where do you begin your search? What kind of features are available? We’re here to answer your questions and help you find the best model for your specific needs.

Our shopping guide will take you through the features you’ll find and considerations you’ll need to make before you buy.

Everything needs to be streamlined and hydrodynamic in the water. While an MP3 player isn’t large enough to significantly affect your lap times, it can become an uncomfortable distraction if it’s not the right size and shape. Small, unobtrusive models are the easiest for most people to adapt to. Some are even compact enough to attach to swim goggles while others may need to be tucked away in a swim cap. The size and shape that's right for you is a matter of personal preference.

You also need to think about the shape and placement of the control buttons and how easy they are to adjust while you're in the water. In some cases, larger buttons on a bigger MP3 player may work better than small buttons on a compact model because it’s easier to operate a bigger button, especially when your hands are wet. People with large hands may find a bigger MP3 player (with larger buttons) easier to control, while people with small hands may be able to use a compact model without a problem.

No matter the size or design, the MP3 player should feel comfortable while wearing and easy to control while in the water.

In general, MP3 players have six to eight hours of play time per charge, though there are a few outliers that have up to 16 hours. Actual play time will depend on a number of factors, including water temperature, volume, and whether or not the MP3 player is using Bluetooth to access music. The majority of models have either a rechargeable lithium ion or lithium polymer battery that takes anywhere from 1.5 to 4 hours to recharge. While these two battery types have similar performance, lithium ion batteries hold a charge longer and are less expensive, making a model that uses this type more economical in the long run.

Waterproof MP3 players may sacrifice some sound quality in favor of keeping the unit small and watertight, but what's the point of having music underwater if it sounds terrible? Look for a combination of size, ease of use, and sound quality. Sound issues may not even start with the MP3 player itself. Where you usually run into trouble are earbuds or headphones that allow water into the ear canal, muffling the sound. You may need to try a few different earbuds or headphones to get the desired sound quality.

Saltwater presents a corrosion problem for just about any material or electronic device. MP3 players work just as well in saltwater as they do fresh, but you’ll need to rinse them off immediately after getting out of the water. If you’ll be heading out into the ocean, consider that the fewer ports of entry the saltwater has, the easier it is to protect and rinse the MP3 player after each use.

MP3 players will come with a 1GB, 2GB, 4GB, or 8GB memory capacity. To give you an idea of what that means for song capacity, 1GB holds approximately 250 songs while 8GB holds around 2,000 songs. If you don't mind a smaller selection and switching out songs more often, you can save money by opting for a model with less memory capacity. Serious music enthusiasts may want to splurge on a model with higher memory capacity.

Most waterproof MP3 players are rated for up to 10 feet of water. Once you get deeper than that, the unit may become compromised. Most people don't need an MP3 player that goes any deeper because they’re swimming in a pool or staying on the surface. However, if you go deeper and want to take your music with you, look for one of the few models that can go to greater depths.

Easy access to basic control features such as pause, shuffle, playback, and repeat is absolutely essential. Some models have the control buttons on the player itself, while others design them into the headphones. Wet fingers may not have the dexterity to scroll through lists and fumble with difficult buttons. The best MP3 players will allow you to easily and quickly access those four basic functions.

Not all MP3 players support all audio file types. You may have MP3, WMV, WAV, FLAC or other files in your library. Make sure you get an MP3 player that supports the format you use most.

There are three basic downloading options and an MP3 player may be capable of more than one.

• Bluetooth: Bluetooth-enabled models can either download songs wirelessly or access a streaming music service via Bluetooth. Some of these models work well while others have a limited range, some as short as a few inches, in which they can access another Bluetooth device.

• USB: Some models have a USB port and cord to plug into another device to download songs. This method of downloading tends to be faster than Bluetooth.

• Mini SD card: Yet another option is the use of a mini SD card onto which you download music then insert the card into the MP3 player. This method takes a few more steps than either Bluetooth or a USB cord but is more reliable that Bluetooth.

How do you want to wear the MP3 player in the water? Some models are a single piece with the earbuds and player integrated into a design that wraps around the ears and behind the neck. Other designs can be attached to a pair of swim goggles and transmit music via Bluetooth to wireless earbuds. Yet another attachment method requires the use of a specially designed swim cap that holds the MP3 player and headphones or earbuds in place.

The method of attachment is a personal choice, so think about how it will affect your swim style. Some people may find it distracting to have a plastic piece behind the neck while others may not find a swim cap comfortable. Models that can be used with wireless earbuds tend to be the least distracting but you have to make sure to get earbuds that fit well so water cannot enter the ear canal.

Some MP3 players only work with a specific type or brand of earbuds or headphones. Others can be used with any compatible pair. The choice of whether to use earbuds or headphones is up to you. Headphones are larger and may be more noticeable to you while in the water. Earbuds, on the other hand, are smaller and may be wireless or wired. Wires will need to be tucked into a swim cap so they don’t drag while in the water.

New technology now provides a third option. Bone conduction technology eliminates the need for an earpiece. The MP3 player attaches to the swim goggles with placement on the cheekbones. The music is then conducted through the cheekbones to the eardrums. They don't require earbuds or headphones in the ears. This technology hasn't been as reliable as either earbuds or headphones but looks promising and can be more comfortable to wear.

There’s a surprising amount of noise underwater. Not only do you need easy access to the volume control but the MP3 player needs to reach a volume that exceeds or dampens other underwater sounds.

Waterproof MP3 players that come as part of a kit can be an economical choice that provides everything at once. They may include goggles, a swim cap, and earbuds. Be sure the kit includes everything you need so you don’t have to buy anything separately.  One potential downside to a kit, however, is that any one or more of the individual elements may not fit well or otherwise be to your liking.

Waterproof MP3 players start around $40. At this price, they may have a wraparound or earbud-style design and come with as much as 8GB of memory.

In the $40 to $100 range are models that come with everything you need, including earbuds or headphones, goggles, and a swim cap if that's how the MP3 player stays in place. You'll also find more wraparound styles with control buttons on the ear-pieces.

At more than $100, you'll find models with bone conduction technology and models that withstand a deeper water depth.

• The type of swimming you do can affect your choice of MP3 player. Pool water isn't likely to knock off your MP3 player but a swift flip turn might, and if you swim in open water, waves could be an issue. You may need a model that's held in place by a swim cap, for example. A serious look at the conditions and water type – fresh or salt – can help you narrow down your choices.

• For your comfort and the best sound, the fit of the earbuds, headphones, or bone conduction technology needs to be impeccable. Models that come with different sized earpieces are often the best choice because they allow you to customize the fit.

• Think about how you’ll wear the MP3 player. If it will be attached to your goggles or looped through a swim cap, make sure you can easily use the buttons once it’s in place.

While our top list was limited to five, there are a few other models out there that didn’t make our list but still perform well. The Delphin Waterproof Streaming Media Player has 8GB of memory so you’re looking at a serious amount of songs. It can be purchased with a headphone or earbud option. The touchscreen is easy to control, if a little small, and it produces good sound.  The Tayogo Waterproof MP3 Player is another model with 8GB of memory but comes in a wrap-around style with the headphones and MP3 player integrated into a single piece. It’s also heat resistant if you want to wear it in the bath or shower.

Q. Do the earbuds or headphones keep water out of my ears?
A. They are designed for this purpose but some are more successful than others. The best place to start is with a good fit. Earbuds that come with several sized earpieces allow you to customize the fit, which will be your best defense against water in the ears. Headphones, too, should fit snug to keep water out.

Q. Can pool chemicals and saltwater cause corrosion?
A. To protect the casing and buttons on a waterproof MP3 player, you should rinse the player and headphones or earbuds with fresh water after exposure to saltwater and chlorinated pool water.

Q. Can I use my waterproof headphones with other MP3 players?
A. Some models can be used with any MP3 player with a jack or that’s Bluetooth capable. However, other models are designed only to be used with a specific MP3 player.