Did someone have my password to attempt to access my account?

There is no way to be 100% positive, but most likely through the iPad. On a ship there are typically 1000’s of passengers. Several may have been looking over your shoulder as you unlocked your iPad.

Once they have the code, it can be used to enter where passwords are stored on your iPad and gain access to iCloud and other services.

Was your iPad locked and 2FA enabled?

If you reuse passwords for multiple accounts then a merchant hack discloses your password and possibly more. Bank and credit card company hacks can disclose lots of personal information. So media too, is a problem. Those little quizzes asking favorite colors, where you were born, favorite food etc. are used to learn the answers to security questions that protect your accounts.