Lay the watermelon on its side and cut the top 1/4 to 1/3 off.
Cut slices into the flesh of the watermelon in a crosshatch pattern without going through the rind.
Make a cut all of the way around the watermelon between the flesh and the rind.
Scoop out the watermelon slices and set them aside on a cutting board.
Hollow out the rest of the watermelon and dump out the juice so that it can be used as a bowl.
Dice enough watermelon to measure one cup. Save the remaining watermelon for another use.
Put the diced watermelon in a bowl and add the cucumbers, peppers, onions, cilantro, jalapenos, lime juice, salt, and black pepper.
Mix everything together and taste the salsa. Add additional lime juice, salt, and black pepper, if needed.
Scoop the watermelon salsa into the hollowed out watermelon bowl. Serve the watermelon salsa directly from the watermelon bowl.