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Watching earlier episodes in season 1 helps you follow the plot and character arcs leading into this episode.

Watch The War Between the Land and the Sea Season 1 Episode 3 Online

Q: Where can I watch “The War Between the Land and the Sea” Season 1 Episode 3 online?

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“The Deep” — Watch "The War Between the Land and the Sea" Season 1 Episode 3 online in HD for free. Check streaming providers, cast, and episode details.

Dec 14, 2025 Season 1 Episode 3 45 min

5.6 ★ ★ ★ ★ ★

28 votes

The War Between the Land and the Sea Season 1

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Season 1 Episode 3 — Aired on Dec 14, 2025 • runs about 45 minutes.

Directed by Dylan Holmes Williams.

Written by Pete McTighe.

Notable cast/guest names in this episode include Russell Tovey, Gugu Mbatha-Raw, Jemma Redgrave, Ruth Madeley.

This page includes 2 official still(s) (when available) plus legal availability links.

Looking for “watch The War Between the Land and the Sea Season 1 Episode 3 online”? This is a legal-only guide with synopsis, stills, and navigation for this season.

Synopsis

Barclay plonge dans les profondeurs de l'univers d'Homo Aqua. Sur la terre ferme, Kate se retrouve seule tandis que Downing Street complote avec l'armée pour changer le cours de la guerre.