Australia (country) has Timor Sea and Arafura Sea on the north, not an ocean. But New Guinea belongs to Australia (continent), so it doesn't actually matter, both sides of the sea are the same continent. Unless we consider only the main landmass of each continent and ignore all islands.

Panama, with it's canal, is entirely in North America too, so the canal doesn't matter anyway.

saltwater between it and Asia

If the Panama Canal doesn't count, neither does the Suez Canal, IMO.