I love discoveries like this! I thought Bosnia and Herzegovina became landlocked after Crotia split from Yugoslavia, but according to Wikipedia:

Bosnia and Herzegovina is an almost landlocked country – it has a narrow coast at the Adriatic Sea, about 20 kilometres (12 miles) long surrounding the town of Neum.

Here’s a map of Bosnia and Herzegovina from OpenStreetMap, with Croatia to the left alongside the Adriatic Sea:

Map centred on Bosnia and Herzegovina, from OpenStreetMap

And here’s the lower part of the country, with its coast centred on Neum:

Map of the Bosnia and Herzegovina coast, centred on Neum, from OpenStreetMap.