Go back. There, is a second passageway that leads up out of the water and to hallway with a door at the end. Open the door and you'll find your way out from there...
Active Mod Files:00 Oblivion.esm01 GTAesgaard_2.esm02 Francesco's Leveled Creatures-Items Mod.esm03 Francesco's Optional New Items Add-On.esm04 Cobl Main.esm [Version 1.72]05 Oscuro's_Oblivion_Overhaul.esm [Version 1.34]06 Mart's Monster Mod.esm [Version 3.7b3p3]07 FCOM_Convergence.esm [Version 0.9.9a7]08 Armamentarium.esm [Version 1.3]09 CM Partners.esm0A Unofficial Oblivion Patch.esp [Version 3.2.2]0B UOP Vampire Aging & Face Fix.esp [Version 1.0.0]0C Oblivion Citadel Door Fix.esp0D DLCShiveringIsles.esp0E Unofficial Shivering Isles Patch.esp [Version 1.4.0]0F Francesco's Optional Chance of Stronger Bosses.esp10 Francesco's Optional Chance of Stronger Enemies.esp11 Francesco's Optional Chance of More Enemies.esp12 Francesco's Optional Leveled Quests-SI only.esp13 Francesco's Optional Leveled Guards.esp14 FCOM_Francescos.esp [Version 0.9.9]15 FCOM_FrancescosItemsAddOn.esp [Version 0.9.9]16 FCOM_FrancescosNamedBosses.esp [Version 0.9.9]17 Fran Armor Add-on.esp18 Fran_Lv30Item_Maltz.esp++ Item interchange - Extraction.esp [Version 0.76]19 RAEVWD Cities.esp [Version 1.4]1A RAEVWD New Sheoth.esp [Version 1.5]1B RAEVWD Imperial City.esp [Version 1.4]1C Cutthroat Merchants.esp1D Enhanced Economy.esp [Version 3.0]1E Map Marker Overhaul.esp [Version 3.0]1F Map Marker Overhaul - SI additions.esp [Version 3.0]20 DLCOrrery.esp21 DLCOrrery - Unofficial Patch.esp [Version 1.0.3]22 DLCMehrunesRazor.esp23 DLCMehrunesRazor - Unofficial Patch.esp [Version 1.0.4]24 DLCSpellTomes.esp25 DLCSpellTomes - Unofficial Patch.esp [Version 1.0.1]26 Cobl Glue.esp [Version 1.72]27 Cobl Si.esp [Version 1.63]28 OOO 1.32-Cobl.esp [Version 1.72]29 FCOM_Cobl.esp [Version 0.9.9]2A Bob's Armory Oblivion.esp2B FCOM_BobsArmory.esp [Version 0.9.9]2C Oblivion WarCry EV.esp2D FCOM_WarCry.esp [Version 0.9.9]2E Oscuro's_Oblivion_Overhaul.esp [Version 1.34]2F OOO-Container_Trap_Instant_Effects.esp [Version 1.33]30 ArmamentariumLLVendors.esp31 ArmamentariumArtifacts.esp [Version 1.3]32 FCOM_Convergence.esp [Version 0.9.9]33 FCOM_RealSwords.esp [Version 0.9.9]34 FCOM_SpawnRatesReduced.esp [Version 0.9.9]35 Mart's Monster Mod - More Wilderness Life.esp [Version 3.7b3]36 FCOM_SaferRoads.esp [Version 0.9.9]37 Mart's Monster Mod - No Pests.esp38 FCOM_NoReaversInGates.esp [Version 0.9.9]39 FCOM_NoAdventurersInGates.esp [Version 0.9.9]3A Mart's Monster Mod - Extra Wounding.esp [Version 3.7b3]3B Mart's Monster Mod - No Carrion Rats.esp [Version 3.7b3]3C Mart's Monster Mod - No Bone Loot.esp [Version 3.7b3]3D Mart's Monster Mod - No Undead Rise.esp [Version 3.7b3]3E Mart's Monster Mod - No Werewolves.esp [Version 3.7b3]3F Mart's Monster Mod - No Lanterns.esp [Version 3.7b3]40 Mart's Monster Mod - Less Reavers.esp [Version 3.7b3]41 Mart's Monster Mod - Safer Quest Locations.esp [Version 3.7b3]42 Mart's Monster Mod - Dungeons of MMM.esp [Version 3.7b3]43 Mart's Monster Mod - Slof Horses Complete.esp [Version 3.7b3]44 Mart's Monster Mod - Diverse Runeskulls Loot.esp [Version 3.7b3]45 FCOM_DiverseGuardUnity.esp [Version 0.9.9]46 FCOM_BobsGuardUnity.esp [Version 0.9.9]47 FCOM_HungersUnitySI.esp [Version 0.9.9]48 Mart's Monster Mod - Shivering Isles.esp49 ArmamentariumLL4OOO.esp [Version 2.0]4A OOO-WaterFish.esp [Version 1.34]4B Ivellon.esp [Version 1.7a]4C GTAesgaard.esp4D GTAesgaard_2.esp4E hackdirtabyss.esp4F HeartOftheDead.esp [Version 6.0.1]50 Kragenir's Death Quest.esp51 KDQ - Rural Line Additions.esp52 Malevolent.esp53 The Ayleid Steps.esp [Version 2.6.1]54 Knights.esp55 Knights - Unofficial Patch.esp [Version 1.0.9]56 TOTF.esp57 TOTF Delayer.esp58 Mart's Monster Mod - City Defences.esp [Version 3.7b3p3]59 FCOM_Knights.esp [Version 0.9.9]5A FCOM_UnofficialFranArmorAddon.esp [Version 0.9.9]5B Harvest [Flora].esp [Version 3.0.0]5C Harvest [Flora] - Shivering Isles.esp [Version 3.0.0]5D Bag of Holding.esp [Version 1.5.0]5E P1DkeyChain.esp [Version 5.00]5F Salmo the Baker, Cobl.esp [Version 3.08]60 Lightweight Potions.esp [Version 1.1]61 Let There Be Darkness - Knights.esp62 Let There Be Darkness - Cyrodiil + SI.esp63 Let There Be Darkness - Mehrunes Razor.esp++ Item interchange - Placement for FCOM.esp [Version 0.76]64 Mart's Monster Mod - Resized Races.esp [Version 3.7b1]65 OOO-Respawn_Month.esp [Version 1.33]++ Cobl Filter Late MERGE ONLY.esp [Version 1.53]66 Bashed Patch, 0.esp67 OOO-Magic_Script_Effect_Fix.esp [Version 1.33]68 TheOubliette.esp