We leave the lovely little beach town of Puerto Morelos with a real sense of disappointment, an unshakable feeling that we really missed out here. Not so much that the seaweed invasion spoilt both the beach and the sea – though that was disappointment enough – but more the fact that I couldn’t shake off the bout of “travel tummy” enough to enjoy the town’s splendid bars and restaurants. Being a beach town, this is probably the best collection we’ve seen in Mexico, but regrettably I just wasn’t up to making the most of it. As we walk home on our last night here – a Friday – after eating…