diff --git a/spec b/spec
index 35a9011c8..7e3dbfcdb 100644
--- a/spec
+++ b/spec
@@ -4131,8 +4131,7 @@ beginseg
     name "ovl_Bg_Goron_Oyu"
     compress
     include "build/src/overlays/actors/ovl_Bg_Goron_Oyu/z_bg_goron_oyu.o"
-    include "build/data/ovl_Bg_Goron_Oyu/ovl_Bg_Goron_Oyu.data.o"
-    include "build/data/ovl_Bg_Goron_Oyu/ovl_Bg_Goron_Oyu.reloc.o"
+    include "build/src/overlays/actors/ovl_Bg_Goron_Oyu/ovl_Bg_Goron_Oyu_reloc.o"
 endseg
 
 beginseg
diff --git a/src/overlays/actors/ovl_Bg_Goron_Oyu/z_bg_goron_oyu.c b/src/overlays/actors/ovl_Bg_Goron_Oyu/z_bg_goron_oyu.c
index b0e79b3db..e32492e9c 100644
--- a/src/overlays/actors/ovl_Bg_Goron_Oyu/z_bg_goron_oyu.c
+++ b/src/overlays/actors/ovl_Bg_Goron_Oyu/z_bg_goron_oyu.c
@@ -15,7 +15,13 @@ void BgGoronOyu_Destroy(Actor* thisx, GlobalContext* globalCtx);
 void BgGoronOyu_Update(Actor* thisx, GlobalContext* globalCtx);
 void BgGoronOyu_Draw(Actor* thisx, GlobalContext* globalCtx);
 
-#if 0
+void func_80B40100(BgGoronOyu* this, GlobalContext* globalCtx);
+void func_80B400C8(BgGoronOyu* this, GlobalContext* globalCtx);
+void func_80B401F8(BgGoronOyu* this, GlobalContext* globalCtx);
+void BgGoronOyu_UpdateWaterBoxInfo(BgGoronOyu* this, GlobalContext* globalCtx);
+void BgGoronOyu_SpawnParticles(BgGoronOyu* this, GlobalContext* globalCtx);
+void func_80B40160(BgGoronOyu* this, GlobalContext* globalCtx);
+
 const ActorInit Bg_Goron_Oyu_InitVars = {
     ACTOR_BG_GORON_OYU,
     ACTORCAT_BG,
@@ -28,31 +34,163 @@ const ActorInit Bg_Goron_Oyu_InitVars = {
     (ActorFunc)BgGoronOyu_Draw,
 };
 
-#endif
+extern Gfx D_06000080;
+extern Gfx D_06000158;
+extern AnimatedMaterial D_06000968;
+extern CollisionHeader D_06000988;
 
-extern UNK_TYPE D_06000968;
-extern UNK_TYPE D_06000988;
+void func_80B40080(BgGoronOyu* this) {
+    this->unk_17E = 1;
+    this->actionFunc = func_80B400C8;
+}
 
-#pragma GLOBAL_ASM("asm/non_matchings/overlays/ovl_Bg_Goron_Oyu/func_80B40080.s")
+void func_80B4009C(BgGoronOyu* this) {
+    this->unk_17E = 0;
+    this->initialActorCutscene = this->dyna.actor.cutscene;
+    this->actionFunc = func_80B40100;
+    this->unk_164 = 20.0f;
+}
 
-#pragma GLOBAL_ASM("asm/non_matchings/overlays/ovl_Bg_Goron_Oyu/func_80B4009C.s")
+void func_80B400C8(BgGoronOyu* this, GlobalContext* globalCtx) {
+    BgGoronOyu_UpdateWaterBoxInfo(this, globalCtx);
+    func_80B401F8(this, globalCtx);
+}
 
-#pragma GLOBAL_ASM("asm/non_matchings/overlays/ovl_Bg_Goron_Oyu/func_80B400C8.s")
+void func_80B40100(BgGoronOyu* this, GlobalContext* globalCtx) {
+    if (ActorCutscene_GetCanPlayNext(this->initialActorCutscene)) {
+        ActorCutscene_StartAndSetUnkLinkFields(this->initialActorCutscene, &this->dyna.actor);
+        this->actionFunc = func_80B40160;
+    } else {
+        ActorCutscene_SetIntentToPlay(this->initialActorCutscene);
+    }
+}
 
-#pragma GLOBAL_ASM("asm/non_matchings/overlays/ovl_Bg_Goron_Oyu/func_80B40100.s")
+void func_80B40160(BgGoronOyu* this, GlobalContext* globalCtx) {
+    static Vec3f D_80B40780 = { 0, 0, 0 };
 
-#pragma GLOBAL_ASM("asm/non_matchings/overlays/ovl_Bg_Goron_Oyu/func_80B40160.s")
+    Math_StepToF(&this->unk_164, 0.0f, 0.2f);
+    this->dyna.actor.world.pos.y = this->dyna.actor.home.pos.y - this->unk_164;
+    BgGoronOyu_UpdateWaterBoxInfo(this, globalCtx);
 
-#pragma GLOBAL_ASM("asm/non_matchings/overlays/ovl_Bg_Goron_Oyu/func_80B401F8.s")
+    if (this->unk_164 <= 0.0f) {
+        ActorCutscene_Stop(this->initialActorCutscene);
+        this->unk_164 = 0.0f;
+        func_80B40080(this);
+    }
 
-#pragma GLOBAL_ASM("asm/non_matchings/overlays/ovl_Bg_Goron_Oyu/func_80B40308.s")
+    func_8019F1C0(&D_80B40780, NA_SE_EV_WATER_LEVEL_DOWN - SFX_FLAG);
+}
 
-#pragma GLOBAL_ASM("asm/non_matchings/overlays/ovl_Bg_Goron_Oyu/func_80B40394.s")
+void func_80B401F8(BgGoronOyu* this, GlobalContext* globalCtx) {
+    Player* player;
+    Vec3f dist;
 
-#pragma GLOBAL_ASM("asm/non_matchings/overlays/ovl_Bg_Goron_Oyu/BgGoronOyu_Init.s")
+    if (Actor_HasParent(&this->dyna.actor, globalCtx)) {
+        this->dyna.actor.parent = NULL;
+        return;
+    }
 
-#pragma GLOBAL_ASM("asm/non_matchings/overlays/ovl_Bg_Goron_Oyu/BgGoronOyu_Destroy.s")
+    player = GET_PLAYER(globalCtx);
+    Math_Vec3f_DistXYZAndStoreDiff(&this->waterBoxPos, &player->actor.world.pos, &dist);
 
-#pragma GLOBAL_ASM("asm/non_matchings/overlays/ovl_Bg_Goron_Oyu/BgGoronOyu_Update.s")
+    if (dist.x >= 0.0f && dist.x <= this->waterBoxXLength && dist.z >= 0.0f && dist.z <= this->waterBoxZLength &&
+        fabsf(dist.y) < 100.0f && player->actor.depthInWater > 12.0f) {
+        func_800B8A1C(&this->dyna.actor, globalCtx, 0xBA, this->dyna.actor.xzDistToPlayer,
+                      fabsf(this->dyna.actor.playerHeightRel));
+    }
+}
 
-#pragma GLOBAL_ASM("asm/non_matchings/overlays/ovl_Bg_Goron_Oyu/BgGoronOyu_Draw.s")
+void BgGoronOyu_UpdateWaterBoxInfo(BgGoronOyu* this, GlobalContext* globalCtx) {
+    WaterBox* waterBox;
+    f32 ySurface;
+
+    if (WaterBox_GetSurface1(globalCtx, &globalCtx->colCtx, this->dyna.actor.world.pos.x, this->dyna.actor.world.pos.z,
+                             &ySurface, &waterBox)) {
+        Math_Vec3s_ToVec3f(&this->waterBoxPos, &waterBox->minPos);
+        this->waterBoxXLength = waterBox->xLength;
+        this->waterBoxZLength = waterBox->zLength;
+    }
+}
+
+void BgGoronOyu_SpawnParticles(BgGoronOyu* this, GlobalContext* globalCtx) {
+    s16 scale;
+    Vec3f pos1;
+    Vec3f pos2;
+    CollisionPoly* poly;
+    s32 pad;
+
+    if ((globalCtx->state.frames % 4) == 0) {
+        Vec3f vel1;
+        Vec3f vel2;
+
+        pos1.x = this->dyna.actor.world.pos.x;
+        pos1.y = this->dyna.actor.world.pos.y + 100.0f;
+        pos1.z = this->dyna.actor.world.pos.z;
+        vel1.x = 0.0f;
+        vel1.y = 2.5f;
+        vel1.z = 0.0f;
+        scale = -200 - (s32)(Rand_ZeroOne() * 50.0f);
+
+        if (BgCheck_EntityRaycastFloor2(globalCtx, &globalCtx->colCtx, &poly, &pos1) < this->waterBoxPos.y) {
+            pos1.y = this->waterBoxPos.y + 10.0f;
+            EffectSsIceSmoke_Spawn(globalCtx, &pos1, &vel1, &D_801D15B0, scale);
+        }
+        pos2.x = (Rand_ZeroOne() * this->waterBoxXLength) + this->waterBoxPos.x;
+        pos2.y = this->waterBoxPos.y + 100.0f;
+        pos2.z = (Rand_ZeroOne() * this->waterBoxZLength) + this->waterBoxPos.z;
+        vel2.x = 0.0f;
+        vel2.y = 0.5f;
+        vel2.z = 0.0f;
+        scale = -200 - (s32)(Rand_ZeroOne() * 50.0f);
+
+        if (BgCheck_EntityRaycastFloor2(globalCtx, &globalCtx->colCtx, &poly, &pos2) < this->waterBoxPos.y) {
+            pos2.y = this->waterBoxPos.y + 10.0f;
+            EffectSsIceSmoke_Spawn(globalCtx, &pos2, &vel2, &D_801D15B0, scale);
+        }
+    }
+}
+
+void BgGoronOyu_Init(Actor* thisx, GlobalContext* globalCtx) {
+    s32 pad;
+    BgGoronOyu* this = THIS;
+    CollisionHeader* colHeader = NULL;
+
+    Actor_SetScale(&this->dyna.actor, 0.1f);
+    DynaPolyActor_Init(&this->dyna, 1);
+    CollisionHeader_GetVirtual(&D_06000988, &colHeader);
+
+    this->dyna.bgId = DynaPoly_SetBgActor(globalCtx, &globalCtx->colCtx.dyna, &this->dyna.actor, colHeader);
+
+    BgGoronOyu_UpdateWaterBoxInfo(this, globalCtx);
+
+    if (thisx->params != 0) {
+        thisx->world.pos.y = thisx->home.pos.y;
+        func_80B40080(this);
+    } else {
+        thisx->world.pos.y = thisx->home.pos.y - 20.0f;
+        func_80B4009C(this);
+    }
+}
+
+void BgGoronOyu_Destroy(Actor* thisx, GlobalContext* globalCtx) {
+    BgGoronOyu* this = THIS;
+
+    DynaPoly_DeleteBgActor(globalCtx, &globalCtx->colCtx.dyna, this->dyna.bgId);
+}
+
+void BgGoronOyu_Update(Actor* thisx, GlobalContext* globalCtx) {
+    BgGoronOyu* this = THIS;
+
+    this->actionFunc(this, globalCtx);
+    BgGoronOyu_SpawnParticles(this, globalCtx);
+}
+
+void BgGoronOyu_Draw(Actor* thisx, GlobalContext* globalCtx) {
+    OPEN_DISPS(globalCtx->state.gfxCtx);
+    func_8012C2DC(globalCtx->state.gfxCtx);
+    AnimatedMat_Draw(globalCtx, Lib_SegmentedToVirtual(&D_06000968));
+    gSPMatrix(POLY_XLU_DISP++, Matrix_NewMtx(globalCtx->state.gfxCtx), G_MTX_NOPUSH | G_MTX_LOAD | G_MTX_MODELVIEW);
+    gSPDisplayList(POLY_XLU_DISP++, &D_06000158);
+    gSPDisplayList(POLY_XLU_DISP++, &D_06000080);
+    CLOSE_DISPS(globalCtx->state.gfxCtx);
+}
diff --git a/src/overlays/actors/ovl_Bg_Goron_Oyu/z_bg_goron_oyu.h b/src/overlays/actors/ovl_Bg_Goron_Oyu/z_bg_goron_oyu.h
index e60a42af2..dba8bb044 100644
--- a/src/overlays/actors/ovl_Bg_Goron_Oyu/z_bg_goron_oyu.h
+++ b/src/overlays/actors/ovl_Bg_Goron_Oyu/z_bg_goron_oyu.h
@@ -8,12 +8,15 @@ struct BgGoronOyu;
 typedef void (*BgGoronOyuActionFunc)(struct BgGoronOyu*, GlobalContext*);
 
 typedef struct BgGoronOyu {
-    /* 0x0000 */ Actor actor;
-    /* 0x0144 */ char unk_144[0x18];
-    /* 0x015C */ BgGoronOyuActionFunc actionFunc;
-    /* 0x0160 */ char unk_160[0x20];
+    /* 0x000 */ DynaPolyActor dyna;
+    /* 0x15C */ BgGoronOyuActionFunc actionFunc;
+    /* 0x160 */ UNK_TYPE unk_160;
+    /* 0x164 */ f32 unk_164;
+    /* 0x168 */ Vec3f waterBoxPos;
+    /* 0x174 */ f32 waterBoxXLength;
+    /* 0x178 */ f32 waterBoxZLength;
+    /* 0x17C */ s16 initialActorCutscene;
+    /* 0x17E */ u16 unk_17E;
 } BgGoronOyu; // size = 0x180
 
-extern const ActorInit Bg_Goron_Oyu_InitVars;
-
 #endif // Z_BG_GORON_OYU_H