Mar sits next to 3 phonetic neighbors — Marie, Mara, and Mare are the closest matches by sound. Most share Mar's Spanish-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"sea"
"from Hadria, from the Adriatic"
"grief, suffering"
"God is gracious"
"noble, exalted, high"
"garden, vineyard"
"dark one, man from the dark sea"
"heavenly, elevated"
"day's eye, daisy flower"
"priceless, inestimable"
"holly garden (via Leslie)"
"peace, safe and sound"
"noble, gracious"
"God is my oath (as diminutive of Elizabeth)"
"man of God, messenger"
"reversed form of Maria, beloved of God"
"rainbow woman"
"heavenly, sacred"
"one who hears, listener"
Similar sound: These names share phonetic patterns with Mar — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Latin origins, giving them the same cultural heritage as Mar.
Rhythm: Mar is a 1-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.