Atlantic at 0-1 years, I live in Cornwall, only about 15 miles from the south coast, 30 from the north.
I saw the Indian at 8 years old when visiting family in South Africa (never been back since although I'd love to go again one day) and if we're including seas I saw the Mediterranean first at 13 from Venice- I think, I was in Italy at 10 but I "only" went to Florence and Rome so I can't remember whether or not I saw the sea while travelling.
I've not seen any of the others so far.
I saw the Indian at 8 years old when visiting family in South Africa (never been back since although I'd love to go again one day) and if we're including seas I saw the Mediterranean first at 13 from Venice- I think, I was in Italy at 10 but I "only" went to Florence and Rome so I can't remember whether or not I saw the sea while travelling.
I've not seen any of the others so far.