GURPS and D&D3.x are different enough that there's going to have to be a lot of "from scratch" anyway - especially at high levels, which this guy is.
Taking it from the top:
700 points - yowza! That puts him up into the superhero/epic range in GURPS terms. However, looking at his actual abilities, he doesn't look all that epic in D&D terms. No magic, no weapons other than his claws and a stone spear - his main abilities seem to be skills, poison, and being incredibly tough to put down for the count - and if you do, he gets four free resurrections.
ST 14, DX 14, IQ 15, HT 15 = Str 14, Dex 14, Con 16, Int 16. GURPS treats Charisma as an advantage ("feat") rather than a stat, but Charisma+1, the Ally Group, and the high levels in Interrogation, Intimidation, and Leadership skils all imply a high Charisma D&D-wise. Few if any of his skills appear Wis-based, so Wis is probably the "dump" stat for him - say 10 or 12.
As written, this guy is very much a plotter and schemer, the sort of BBEG who prefers to lurk in the shadows while minions do the fighting and dying. Class-wise, looks like Rogue is the best fit, perhaps with a few levels of Ranger (= Two-Weapon Fighting and favored enemy:Atlanteans), perhaps a few levels of Assassin or another prestige class..
Move 7 = Base Speed 40
Dodge 8, Parry 11 : Good but not great = so-so Dex modifier to AC
Ally Group = Leadership ( a very close fit : 75pt minion = lvl 1 NPC)
Ambidexterity = Two-Weapon Fighting
Gills = can breathe water, Amphibious = can also breathe air, has natural Swim speed
Cast Iron Stomach = can eat anything, including rotten food; no exact D&D equivalent, but should probably give a +4 vs ingested poisons.
Combat Reflexes = Improved Initiative & Lightning Reflexes
Cool = ranks in Concentration, or Iron Will.
DR 12, PD 3 = natural armor, almost as good at deflecting blows as full plate, and better at soaking damage. Say natural armor AC 7 and Damage Reduction 3/-
Extra Lifex4: He can come back to life after being slain, four times. In D&D, would be a unique ability, a "dark god's blessing" or some such. This is pretty much his only epic-level ability.
Faz Sense = Blindsense(vibration-based)
Fit = Endurance
Hard to Kill+5 = bonus on rolls to stabilize/recover, and +1 to Fort saves.
High Pain Threshold = bonus to resist being stunned, dazed, nauseated, sickened, etc. (Great Fortitude?)
Immune to Disease: like it says.
Less sleep = like an elf?
Patron = no direct equivalent. The Black Smoker Entity sounds like some sort of evil god, though, which would neatly explain the Extra Life.
Pressure Support = no direct equivalent. Immunity to deep-sea pressure.
Rapid Healing = Faster Healing feat from Complete Warrior.
Sharp Claws = natural claw attack, he only took the 25-pt level so no bonus damage.
Temperature Tolerance 5 = Cold resistance 5 and Fire resistance 5.
Unaging = doesn't age. Not considered worth points in D&D.
Venom, 2 levels = a moderately-potent venom (probably doing 1d6 Con damage) with a racial +1 to its DC.
Reduced Manual Dexterity = -1 penalty to "fine motor control" skills, such as Open Lock, Disable Device, Forgery, Sleight of Hand, Craft, and some types of Perform.
The other Disads are mostly "roleplaying" and hence not "worth points" in D&D. However, they paint a picture of a guy who loves to hurt others, but has very tight self control = almost certainly Lawful Evil. Also, with the slit eyes, scaly skin, claws, amphibious, etc., he sounds more and more like some sort of sahuagin. Adding the Fiendish template would provide the energy resistances and damage reduction. (Half-fiend goes too far, throwing in a mess of spell-like abilities that don't fit this guy's base concept.)
Skills: anything he has 8 GURPS points in should be maxed-out in D&D. Otherwise, assume 1 GURPS point = 2 D&D ranks, then adjust the results as seems good to you.
