There are wire guided torpedoes and missiles that carry a spool with them and pay it out as they travel.  Presumably this is a good thing because it can&#x27;t be intercepted and jammed.  Anyway, that missile carries 4200m of wire, which would be plenty for an ROV to explore most of the cave in the article before sending people, who could follow its wire.<p><a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;BGM-71_TOW" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;BGM-71_TOW</a>