This dream presents several interesting themes that can be explored.

1. Travel and Exploration: The journey by water to an island signifies a quest for new experiences or knowledge. Water often symbolizes emotions and the subconscious, suggesting that you may be exploring your feelings or new aspects of your life.
2. Companionship: The presence of the two girls may represent aspects of yourself or friends in your life. They could symbolize support and friendship during your exploration.
3. Conflict and Danger: The initial friendliness of the island's inhabitants turning into a threat when they try to take your Apple Watches could reflect feelings of vulnerability or fear of losing something valuable in your waking life. The Apple Watch can symbolize time, technology, or personal achievement, indicating that you might feel your personal power or achievements are under threat.
4. Escape and Resilience: Your ability to escape by swimming shows resourcefulness and determination. This suggests that you possess the strength to navigate through challenges and protect what is important to you.

Overall, this dream may be encouraging you to reflect on your current life journey, assess your relationships, and consider how you deal with perceived threats or challenges. It could also be a reminder to value your personal achievements and the support of friends as you navigate through complex situations.