Waterlox is a marine finish that is Tung Oil based. It is a penetrating finish, and protects not only against water, but against sun, wind, rain and salt - though you probably don't have THAT harsh an environment in your kitchen. Waterlox is non-toxic when cured, but should not be used for cutting as scratches do not easily sand out. Waterlox will darken wood and dries to either a satin, semi-gloss or high gloss finish depending on the product used.
Waterlox can be applied with a cloth, or even with a roller or brush. Reapplication is infrequently needed, but if desired, new coats can be applied directly over the old. Examples of countertops with Waterlox can be seen at
DeVos Custom Woodworking.
Butcherblock Counters - Finish Options
Waterlox Finish in Original Formula and Medium/High Gloss Sheen