When is high tide in Pokemon sapphire?

Answer 1

Remember when you set your clock in your bedroom at the beginning of the game? This is where it comes in handy.

The tides go in and out every 6 hours.

3am-9am: High Tide

9am-3pm: Low Tide

3pm-9pm: High Tide

9pm-3am: Low Tide

The times go by the clock you set in your room.

Good luck.