Wearing jewellery in the ocean is absolutely fine but it is important to know that salt water and the ocean are corrosive and can be a harsh environment for your jewellery. So, although your jewellery will not tarnish or turn your skin green, the gold plating can fade a lot faster in this environment becoming lighter and revealing the silver underneath.
The thing that you should be careful of it is harsh products in the shower. Tap water will rarely have affect or react with your jewellery. That being said, if you shower of take a bath and submerge your jewellery in harsher chemicals this can compromise the jewellery.
Swimming in water with chlorine with your jewellery is not recommended as you will be coming into contact with water that has chemicals that will interact with you jewellery more dramatically than fresh water.
Hand Sani and Jewellery are simply not good friends, please avoid your jewellery to have contact with it specially with your rings.