In French Polynesia, most of the sharks that cross your path are black tips. They are harmless sharks for humans. They're probably more afraid of you than you are of them! They are usually between 1m and 1.50m.
"Should we pay for an excursion to see the sharks?"
Not. Simple and effective answer!
There's plenty of opportunity to see sharks just by strolling through the lagoon, swimming, kayaking or boating. The shark is a curious animal, it sneaks up and then leaves as fast as it arrived.
On the other hand, if you want to guarantee the meeting, you can go to spots where they are "residents".
If you own a kayak, on your own or otherwise via an excursion. All providers offer a "Rays and Sharks" stop. There are several spots in Moorea where they are more or less sedentary by feeding. However, this practice, very common in Polynesia, is much maligned. I personally think that shark feeding should not be practiced. It's up to you.
The lagoonarium is a great spot to meet sharks. It is a motu arranged. You can go there by shuttle (paying) to the day or half day and enjoy the facilities on site: sheds, meals etc but it is also possible to reach the motu by kayak to come and visit the coral garden (free). Ropes have been set up to swim safely between the potatoes and withstand the strong currents that pass through it. The common trend also means rich flora and fauna: many fish, colorful corals etc will be at the appointment, a real aquarium! And at the turn of a potato you will come across sharks and stingrays.
On the right: the lagoon and the buoys that indicate the water course to follow with the ropes.
For visitors who have paid for their day on the motu, a show of rays and sharks is offered 2x per day. And by show, I mean feeding. But if you take your kayak and come to see the coral garden at 11am or 2pm you will have the chance to see a profusion of fish, rays and sharks in the lagoon, attracted by feeding. I advise you of course not to support the approach, ie, do not feed and do not touch wild animals but also, do not attend the shows, . Just by staying away, the show will be extra and bonus, you will not have the legs of ten tourists in your photos /videos.
The Ti Baskets is located to the west of the island. For 500FCP an hour (about 5 euros), you can rent a kayak and paddle to the spot of rays and sharks. You can see the spot from the pontoon of the hotel, about 500m away. They are used to being fed by day-trippers there so their presence is guaranteed. The spot is so famous that it is shown on google.maps and maps.me!
Take the opportunity to make a robinsonnade on the white sand beach of the nearby motu!