The Swordfish is a Tier 5 ship in the Nautic Series mod. Like other ships in the upgrade path, it is a rammer. It is a weaker, Tier 5 version of the Narwhal, which it upgrades into.
This ship is a poor ship for various reasons, so it is recommended to powermine base to Level 4 with the Cuttlefish and skip to Narwhal without upgrading this ship. Its only predecessor, the Cuttlefish, mines at least as fast the Swordfish. Its mass is also not much better than the Squid, another exclusive predecessor.