|Home world:||Planet Earth (Giants of Light Timeline)|
|First appearance:||Ultraman Dyna episode 23 "Dream Fortress"|
Subtitle: Deep Sea Dragon (深海竜 Shinkairyū?)
- Height: Unknown
- Length: 155 m
- Weight: 52, 000 t
- Origin: Undersea, somewhere near the TPC research base Triton J2
Everything seemed to be going normal at the undersea base of Super GUTS's ocean division until a mysterious red energy bolt destroyed a third of the complex. Super GUTS sent the Japanese division to investigate the situation to make sure it was not the cause of a monster. It did not take long for Super GUTS to find Diplas, the monster responsible, as he was heading for them. The GUTSMAVI and Diplas fought each other with neither side gaining the upper hand, forcing Super GUTS to shut off the submarine's lights so the cobra-like sea serpent could not locate them. However, this did not work as Diplas easily found them as GUTSMAVI tried to make a run for the surface. When Diplas had the GUTSMAVI trapped in a trench, the submarine fired a few laser torpedoes to cause a rock slide onto him, burying him alive. As Super GUTS was executing a rescue mission in the ocean division's base and the shield was reactivated, the ruby on Diplas's antenna sensed it and seemingly awoke him and allowed him to break through the rocks. Shin used the GUTSMAVI to distract Diplas as Super GUTS continued rescuing the injured crew and quickly turned into Ultraman Dyna just as the cobra-like sea serpent used an energy bolt on the GUTSMAVI. However, after a use of the Dyna Ball on him, Diplas became stronger and knocked out Dyna by constriction even when he went into Strong Mode. Diplas went after Super GUTS, only for them to blast his antenna off. Just as Diplas was about to execute a counterattack, Dyna used the Solgent Beam to destroy the cobra-like sea serpent.
- Adept Swimmer: Diplas can swim at medium speeds and can survive depths as low as 6200 meters.
- Burrowing: Diplas can burrow at low speeds.
- Energy Bolts: Diplas can fire red bolts of energy from the ruby on his antenna. These bolts can also be used to stun enemies while he is in physical contact with them.
- Coil: Diplas can use his body to coil around enemy limbs and knock them off balance or constrict them to death.
- Beam Absorb: Diplas can absorb beam attacks to make his energy bolts more powerful.
Diplas's nose is somewhat flammable enough to cause fire even underwater.