Peel, core, and slice pineapple.

Pack pineapple into a glass container.

Add rum to cover the pineapple.

Seal container and store in a cool place for 4-5 days, tasting occasionally.

Strain rum through a sieve, bottle, and refrigerate for up to two weeks.

In a saucepan, bring water and diced ginger to a boil.

Add sugar, stirring until dissolved.

Reduce heat to low and simmer for 1 hour.

Remove from heat and cool to room temperature.

Strain through a sieve, bottle, and refrigerate for up to one month.

In a 14-oz glass, muddle spearmint, lime juice, and ginger syrup.

Fill the glass with crushed ice.

Add pineapple-infused rum.

Stir to incorporate flavors.

Add more crushed ice.

Top with soda water.

Stir once.

Garnish with mint sprig and pineapple spear.