In a medium saucepan over medium heat, add the sugar and the water. Continue to cook until the sugar dissolves, about 5 minutes.
In a large nonreactive glass container, add the Bacardi, warm simple syrup, and pineapple slices. Let marinate for 1 hour.
Heat a grill to medium-high heat. Being very careful, add the pineapple slices one at a time and let cook for 30 seconds per side. Flip and continue on other side.
Remove from heat when the pineapple is well marked. Place a couple slices of grilled pineapple on a plate and serve with coconut ice cream. Sprinkle with sea salt and serve.