100k is a good down payment, surely you can find a beachside condo at 500k somewhere on the east coast. Can’t speak to the west coast.

You can likely get some revenue back from it by Airbnbing it out when you aren’t around.

Timeshares are an option, a lot of them are scams but some people do have success with them if you do your research.

Ultimately don’t make yourself house poor. 100k also buys a lot of stays at beach hotels or trips to Mexico, DR etc.