I am looking for signs of the 80s to convince me but at the moment I'm seeing earlier. Here is my similarly styled 1980s Topshop dress for comparison, keeping in mind this dress was commercially produced, the large, almost oversize, collar continues unbroken round the back and it has a nylon zip underneath, you have to duck into it. The skirt has a built in underskirt, upper half satin, lower net ruffles.
Thinking of my own 80s version, my thoughts are your dress has no lining, hence it probably would have been worn with garments underneath, such as a slip and/or petticoat, which was commonplace in the 50s/60s but not so much in the 80s/90s.
The collar being open at the back allows a proper zip opening to get into which is more work to create. I haven't seen a photo of the back of the collar but it appears to have sharp pointed lapels, I have a few 80s dresses in this style and they all have collars that continue round the back like a drape.
I also thought when the water-skiier was mentioned, that wearing a swimming cap with a bikini was more fashionable in the 50s-60s and that I couldn't recall one being worn with a fashion swimsuit in the 80s, only sporty swimsuits.
I can't tell from just the photos so could you measure the length of the skirt from waist to hem please? and show a photo of the back of the dress, to see the back collar shape properly.