1) Crab racing- You can take part in a crab race and gamble your money on the crab you think is going to win.
2) Finding sea cucumbers- Sea cucumbers are animals which walk very slowly on the ocean bed. You can spot many near the shore. You can catch them and make authentic Maldivian soup out of them. Sounds gross but is authentic
3) Snorkelling at coffee beans shore- Most of the people snorkel in the deep sea part of Maldives but very few people actually snorkel in this place. This doesn't have a very deep shore, you can stand on the shore but swimming here and looking at the fishes is amazing because it is not very crowded. Here's the rule, if the place is more crowded then less fishes will come to you, instead snorkel here so that there are more fishes coming to you.
4) Mosque in Male- Very few people actually leave their hotels and go to explore Male. Male has a mosque which is very beautiful and it is worth it. You should totally visit.
5) Sting Ray feeding- There's a place in Maldives where you can feed sting rays. This is rare and you can't do it in many places so you might as well make the most of your trip. Watch them open their mouths!