In modern times, I think that there have always been two varieties of swimming.
Swimming up and down indoor pools is foremost in the public conscientiousness because it can be associated with competitive sport at the highest level.
Outdoor swimming in seas, rivers and lakes, with rare exceptions, is much less associated with competitiveness and therefore regarded as a largely recreational activity. Some people take it to extremes, however, by swimming in very cold waters with minimal thermal protection.
As you say, surface swimming is still swimming and may not require a narrower definition to serve particular aquatic actvities. This said, I prefer a descriptive approach when addressing linguistic usage rather than prescription or proscription and hence I say what I find.