Pictured above are the TYR Special Ops (top), Aqua Sphere Kayenne (right), and Speedo Vanquisher (bottom left). Ranked by field of vision from widest to narrowest they are: Aqua Sphere, TYR, then Speedo.
For open water swimming a wide field of vision is a key consideration. Unlike the controlled environment of the pool, in open water not only do you often have cloudy water and buoys to navigate, but you are contesting with a crowd of swimmers unless you are the fastest or the slowest swimmer in the bunch. A popular pool goggle like the Speedo Speed Socket offers a comfortable fit and good leak protection, but it means you have very little peripheral vision. Not only does this lead to the risk of going off course or getting tangled with another swimmer, but it also equates to much more sighting and looking around, which is the key limiter to quality body position and swim stroke in open water.
Therefore, although many buy a second pair of goggles for open water swimming solely for a tinted lens, you should also consider how much peripheral vision is on offer. To the three pictured above, I would add the Maru Groove as a 4th option, but would not go any narrower than the Speedo Vanquisher for open water training or racing. The benefits of a better sense of what’s around you are high. In fact, I wear a wide field pair in crowded Master’s swims in order to have a better sense of where all the other swimmers are in my lane. Like any goggle, these will fit differently for everyone. The Speedos have replaceable nose pieces with different sizes and the Aqua Spheres come in normal and small. The best option is to borrow a pair from a friend and see how they fit for you. Either way though, you won’t regret going with a wider view.