Cushendun bay rainwater phenomenon

Been sitting here today looking at the strange surface effects on the water in the bay, and I’ve just realised I know what’s causing it.
A naturalist in New Zealand told us how rain entering Milford sound ‘floated’ on the seawater leaving a layer up to a meter deep,
It’s been raining for 48 hours here and the river water is clearly floating over the seawater and butting up against the incoming tide in what here here looks like a wave but is actually a stationary wave