I just do tea with milk and sugar before morning swims. A boiled egg after the swim gives me some fuel.
I like a protein shake blended with banana; it makes a nice protein smoothie! It feels light and packed with energy. I feel sick if I eat something heavy before training.
Green tea and a weed cookie.
A glass of water with half a lime juiced and a pinch of mineral salt, and a cup of black coffee. Breakfast of champions.
Celsius before swimming and Gatorade during breaks works for me.
I usually have 2 scoops of peanut butter or drink coconut water. I dislike a full stomach, so I keep my pre-swim snacks light.
I haven’t tried it, but there’s plenty of science showing that beets—juice or whole—boost performance due to nitric oxide.
Pistachios 
.
Just a couple of dried apricots.
Oatmeal works really well for me without making me feel full during my swim. I do need to eat it at least an hour or two before getting in the pool.
Banana. 
I swim in open water; it sits very lightly in my stomach.
I prefer swimming fasted in the morning, but if I’ve had an early dinner the night before, I might have a stewed apple about 20 minutes before my swim. It’s the easiest thing to digest right before an hour of swimming.
Two packets of ramen, then two frozen burritos.
It’s 1997, and I’m 16.
Eat anything you want. Calories are calories.