Where does “seaport” come from?

I need to work through this chain carefully, as it appears to have some repetition and unclear structure. The chain given is: English sea | Latin porta | Latin portare | Proto-Indo-European per- | Proto-Indo-European per- | Proto-Indo-European sed- | Proto-Indo-European sed- | Proto-Indo-European per- This seems problematic because: 1. "sea" and "port" are two different morphemes in "seaport" 2. The chain shows Latin porta (gate/door) and portare (to carry), which don't directly connect to "sea" 3. There are duplicate entries and the chain structure is unclear However, following the instruction to "state only what the chain supports" and work with what's given: the chain appears to trace "port" (from Latin porta/portare relating to carrying/passage) but doesn't actually explain "sea." Given

seaport (English): A town or harbour with facilities for seagoing...

Definitions

  1. A town or harbour with facilities for seagoing...

Ancestry of “seaport”, step by step

seaport traces back through two separate lines of ancestry.

via English Port

StepLanguageWordMeaning
1EnglishPortUniversity of Portsmouth, used especially following post-nominal letters indicating status as a graduate
2EnglishportfolioA case for carrying papers, drawings,...
3Italianportafogliowallet, billfold; portfolio
4Italianfogliosheet
5Latinfoliuma leaf; a petal; a sheet or leaf of paper
6Proto-Italic*foljom
7Proto-Indo-Europeanbʰolh₃yomleaf
8Proto-Indo-Europeanbʰleh₃-bloom, flower
9Proto-Indo-Europeanbʰel-to sound; to speak, roar, bark; shiny, white; to...
10Proto-Indo-Europeanbʰōl-

via English sea

StepLanguageWordMeaning
1EnglishseaA large body of salt water; A lake, especially if...
2Middle Englishseesea, ocean; A body of water, a lake; seat, chair
3Old Englishsea, lake
4Proto-West Germanicsaiwisea
5Proto-Germanicsaiwizsea, ocean
6Proto-Germanicsīhwanąto filter
7Proto-Indo-Europeanseykʷ-to moisten; to filter
8Proto-Indo-Europeansey-to be wet; dribble; run; to stretch one's arm;...
Every word from Proto-Indo-European bʰōl-