Now you begin to see why they acquired submarines. I'm sure they are used to patrol the shallow waters around the island.
Singapore to splash $1.8 billion on four Invincible-class submarines
https://www.navaltoday.com/2023/01/...8-billion-on-four-invincible-class-submarines
If a sub is "invincible" why is there a need for four of them? One can do the job.