diff --git a/src/overlays/actors/ovl_Bg_Ikana_Rotaryroom/z_bg_ikana_rotaryroom.c b/src/overlays/actors/ovl_Bg_Ikana_Rotaryroom/z_bg_ikana_rotaryroom.c
index 94eec2c1d6..77bf925314 100644
--- a/src/overlays/actors/ovl_Bg_Ikana_Rotaryroom/z_bg_ikana_rotaryroom.c
+++ b/src/overlays/actors/ovl_Bg_Ikana_Rotaryroom/z_bg_ikana_rotaryroom.c
@@ -7,6 +7,7 @@
 #include "z_bg_ikana_rotaryroom.h"
 #include "overlays/actors/ovl_Bg_Ikana_Block/z_bg_ikana_block.h"
 #include "overlays/actors/ovl_En_Torch2/z_en_torch2.h"
+#include "overlays/actors/ovl_En_Water_Effect/z_en_water_effect.h"
 #include "objects/object_ikana_obj/object_ikana_obj.h"
 
 #define FLAGS (ACTOR_FLAG_10 | ACTOR_FLAG_20)
@@ -679,7 +680,8 @@ void func_80B81570(BgIkanaRotaryroom* this, PlayState* play) {
         sp70.y += this->dyna.actor.world.pos.y;
         sp70.z += this->dyna.actor.world.pos.z;
 
-        Actor_Spawn(&play->actorCtx, play, ACTOR_EN_WATER_EFFECT, sp70.x, sp70.y, sp70.z, 0, 0, 0, 1);
+        Actor_Spawn(&play->actorCtx, play, ACTOR_EN_WATER_EFFECT, sp70.x, sp70.y, sp70.z, 0, 0, 0,
+                    ENWATEREFFECT_TYPE_FALLING_ROCK_SPAWNER);
     }
 
     Matrix_Pop();
diff --git a/src/overlays/actors/ovl_Boss_03/z_boss_03.c b/src/overlays/actors/ovl_Boss_03/z_boss_03.c
index 23aa023dac..380ef6f0b4 100644
--- a/src/overlays/actors/ovl_Boss_03/z_boss_03.c
+++ b/src/overlays/actors/ovl_Boss_03/z_boss_03.c
@@ -724,7 +724,7 @@ void Boss03_ChasePlayer(Boss03* this, PlayState* play) {
 
             if (sp43 != 0) {
                 Actor_Spawn(&play->actorCtx, play, ACTOR_EN_WATER_EFFECT, player->actor.world.pos.x, this->waterHeight,
-                            player->actor.world.pos.z, 0, 0, 0x78, ENWATEREFFECT_309);
+                            player->actor.world.pos.z, 0, 0, 0x78, ENWATEREFFECT_TYPE_GYORG_RIPPLES);
                 Boss03_PlayUnderwaterSfx(&this->actor.projectedPos, NA_SE_EN_KONB_SINK_OLD);
             }
 
@@ -1055,7 +1055,7 @@ void Boss03_Charge(Boss03* this, PlayState* play) {
             play_sound(NA_SE_IT_BIG_BOMB_EXPLOSION);
             func_800BC848(&this->actor, play, 20, 15);
             Actor_Spawn(&play->actorCtx, play, ACTOR_EN_WATER_EFFECT, 0.0f, this->waterHeight, 0.0f, 0, 0, 0x96,
-                        ENWATEREFFECT_30C);
+                        ENWATEREFFECT_TYPE_GYORG_SHOCKWAVE);
 
             // Player is above water && Player is standing on ground
             if ((this->waterHeight < player->actor.world.pos.y) && (player->actor.bgCheckFlags & 1)) {
@@ -1528,7 +1528,7 @@ void Boss03_DeathCutscene(Boss03* this, PlayState* play) {
             if ((this->workTimer[WORK_TIMER_UNK0_C] == 0) && ((this->waterHeight - 100.0f) < this->actor.world.pos.y)) {
                 this->workTimer[WORK_TIMER_UNK0_C] = Rand_ZeroFloat(15.0f) + 15.0f;
                 Actor_Spawn(&play->actorCtx, play, ACTOR_EN_WATER_EFFECT, this->actor.world.pos.x, this->waterHeight,
-                            this->actor.world.pos.z, 0, 0, 0x78, ENWATEREFFECT_309);
+                            this->actor.world.pos.z, 0, 0, 0x78, ENWATEREFFECT_TYPE_GYORG_RIPPLES);
 
                 if (this->actionFunc == Boss03_DeathCutscene) {
                     if ((D_809E9840 % 2) != 0) {
@@ -2012,7 +2012,7 @@ void Boss03_Update(Actor* thisx, PlayState* play2) {
             }
 
             Actor_Spawn(&play->actorCtx, play, ACTOR_EN_WATER_EFFECT, this->actor.world.pos.x, this->waterHeight,
-                        this->actor.world.pos.z, 0, 0, 0x78, ENWATEREFFECT_309);
+                        this->actor.world.pos.z, 0, 0, 0x78, ENWATEREFFECT_TYPE_GYORG_RIPPLES);
 
             this->unk_280 = 27;
             this->unk_284 = this->actor.world.pos.x;
diff --git a/src/overlays/actors/ovl_Dm_An/z_dm_an.c b/src/overlays/actors/ovl_Dm_An/z_dm_an.c
index 64b6a7a98a..4cd28f454c 100644
--- a/src/overlays/actors/ovl_Dm_An/z_dm_an.c
+++ b/src/overlays/actors/ovl_Dm_An/z_dm_an.c
@@ -160,7 +160,7 @@ Actor* func_80C1C8E8(PlayState* play) {
         }
 
         tempActor = foundActor->next;
-        if (tempActor == NULL || NULL) {
+        if (tempActor == NULL || false) {
             foundActor = NULL;
             break;
         }
diff --git a/src/overlays/actors/ovl_Dm_Gm/z_dm_gm.c b/src/overlays/actors/ovl_Dm_Gm/z_dm_gm.c
index 2b9c62e190..b51f4df8dd 100644
--- a/src/overlays/actors/ovl_Dm_Gm/z_dm_gm.c
+++ b/src/overlays/actors/ovl_Dm_Gm/z_dm_gm.c
@@ -1,7 +1,7 @@
 /*
  * File: z_dm_gm.c
  * Overlay: ovl_Dm_Gm
- * Description: Anju (cutscene) (duplicate of Dm_An?)
+ * Description: Complete duplicate of Dm_An
  */
 
 #include "z_dm_gm.h"
diff --git a/src/overlays/actors/ovl_En_Hs2/z_en_hs2.c b/src/overlays/actors/ovl_En_Hs2/z_en_hs2.c
index 3e6ab858fe..a251dd1133 100644
--- a/src/overlays/actors/ovl_En_Hs2/z_en_hs2.c
+++ b/src/overlays/actors/ovl_En_Hs2/z_en_hs2.c
@@ -1,7 +1,7 @@
 /*
  * File: z_en_hs2.c
  * Overlay: ovl_En_Hs2
- * Description: Blue Target Spot (?)
+ * Description: Near-empty actor. Does nothing, but can be targeted.
  */
 
 #include "z_en_hs2.h"
diff --git a/src/overlays/actors/ovl_En_Tag_Obj/z_en_tag_obj.c b/src/overlays/actors/ovl_En_Tag_Obj/z_en_tag_obj.c
index db6a9d172d..0d39a0db2e 100644
--- a/src/overlays/actors/ovl_En_Tag_Obj/z_en_tag_obj.c
+++ b/src/overlays/actors/ovl_En_Tag_Obj/z_en_tag_obj.c
@@ -1,7 +1,7 @@
 /*
  * File: z_en_tag_obj.c
  * Overlay: ovl_En_Tag_Obj
- * Description:
+ * Description: Unused Seahorse Spawner
  */
 
 #include "z_en_tag_obj.h"
diff --git a/src/overlays/actors/ovl_En_Tanron6/z_en_tanron6.c b/src/overlays/actors/ovl_En_Tanron6/z_en_tanron6.c
index 45459e8b38..ceac1e116e 100644
--- a/src/overlays/actors/ovl_En_Tanron6/z_en_tanron6.c
+++ b/src/overlays/actors/ovl_En_Tanron6/z_en_tanron6.c
@@ -1,7 +1,7 @@
 /*
  * File: z_en_tanron6.c
  * Overlay: ovl_En_Tanron6
- * Description: Swarm of Giant Bees
+ * Description: Unused invisible enemy. Only draws a circle shadow.
  */
 
 #include "z_en_tanron6.h"
diff --git a/src/overlays/actors/ovl_En_Water_Effect/z_en_water_effect.c b/src/overlays/actors/ovl_En_Water_Effect/z_en_water_effect.c
index 92bec240eb..fc1ad7279b 100644
--- a/src/overlays/actors/ovl_En_Water_Effect/z_en_water_effect.c
+++ b/src/overlays/actors/ovl_En_Water_Effect/z_en_water_effect.c
@@ -1,7 +1,15 @@
 /*
  * File: z_en_water_effect.c
  * Overlay: ovl_En_Water_Effect
- * Description: Water splashing effect (used for Gyorg)
+ * Description: Water/rock drop spawner and Gyorg water splashing effect
+ *
+ * This actor serves two purposes:
+ * - It can act as a "spawner" for either water drops or flaming rocks. This
+ *   spawner can be placed in the ceiling to drop these repeatedly.
+ * - It is also used to control various water splashing effects for the Gyorg
+ *   fight. Specifically, it handles the splashing that is caused when it
+ *   enters or exits the water, and it handles the shockwave that is created
+ *   when it rams the center platform.
  */
 
 #include "z_en_water_effect.h"
@@ -85,27 +93,30 @@ void EnWaterEffect_Init(Actor* thisx, PlayState* play) {
     this->actor.flags &= ~ACTOR_FLAG_1;
     this->unk_DC4 = Rand_ZeroFloat(100.0f);
 
-    if (this->actor.params == ENWATEREFFECT_1) {
+    if (this->actor.params == ENWATEREFFECT_TYPE_FALLING_ROCK_SPAWNER) {
         this->actor.update = func_80A59C04;
         this->actor.draw = func_80A5A184;
         this->unk_DC6 = Rand_ZeroFloat(100.0f) + 60.0f;
-    } else if ((this->actor.params == ENWATEREFFECT_309) || (this->actor.params == ENWATEREFFECT_30A) ||
-               (this->actor.params == ENWATEREFFECT_30B) || (this->actor.params == ENWATEREFFECT_30C)) {
+    } else if ((this->actor.params == ENWATEREFFECT_TYPE_GYORG_RIPPLES) ||
+               (this->actor.params == ENWATEREFFECT_TYPE_GYORG_PRIMARY_SPRAY) ||
+               (this->actor.params == ENWATEREFFECT_TYPE_GYORG_SECONDARY_SPRAY) ||
+               (this->actor.params == ENWATEREFFECT_TYPE_GYORG_SHOCKWAVE)) {
         this->actor.update = func_80A5A534;
         this->actor.draw = func_80A5A6B8;
         this->actor.shape.rot.y = Rand_ZeroFloat(0x10000);
         Actor_SetScale(&this->actor, this->actor.shape.rot.z * 0.0002f);
 
-        if (this->actor.params == ENWATEREFFECT_309) {
+        if (this->actor.params == ENWATEREFFECT_TYPE_GYORG_RIPPLES) {
             Actor_Spawn(&play->actorCtx, play, ACTOR_EN_WATER_EFFECT, this->actor.world.pos.x, this->actor.world.pos.y,
-                        this->actor.world.pos.z, 0, 0, this->actor.shape.rot.z, 0x30A);
+                        this->actor.world.pos.z, 0, 0, this->actor.shape.rot.z, ENWATEREFFECT_TYPE_GYORG_PRIMARY_SPRAY);
             Actor_Spawn(&play->actorCtx, play, ACTOR_EN_WATER_EFFECT, this->actor.world.pos.x, this->actor.world.pos.y,
-                        this->actor.world.pos.z, 0, 0, this->actor.shape.rot.z, 0x30B);
-        } else if (this->actor.params == ENWATEREFFECT_30A) {
+                        this->actor.world.pos.z, 0, 0, this->actor.shape.rot.z,
+                        ENWATEREFFECT_TYPE_GYORG_SECONDARY_SPRAY);
+        } else if (this->actor.params == ENWATEREFFECT_TYPE_GYORG_PRIMARY_SPRAY) {
             this->unk_DC4 = -3;
-        } else if (this->actor.params == ENWATEREFFECT_30B) {
+        } else if (this->actor.params == ENWATEREFFECT_TYPE_GYORG_SECONDARY_SPRAY) {
             this->unk_DC4 = -6;
-        } else if (this->actor.params == ENWATEREFFECT_30C) {
+        } else if (this->actor.params == ENWATEREFFECT_TYPE_GYORG_SHOCKWAVE) {
             this->unk_DC4 = 23;
         }
 
@@ -620,7 +631,8 @@ void func_80A5A6B8(Actor* thisx, PlayState* play2) {
     Matrix_Push();
     Matrix_Push();
 
-    if ((this->actor.params == ENWATEREFFECT_309) || (this->actor.params == ENWATEREFFECT_30A)) {
+    if ((this->actor.params == ENWATEREFFECT_TYPE_GYORG_RIPPLES) ||
+        (this->actor.params == ENWATEREFFECT_TYPE_GYORG_PRIMARY_SPRAY)) {
         if (this->unk_E2C > 1.0f) {
             func_8012C2DC(play->state.gfxCtx);
             AnimatedMat_Draw(play, Lib_SegmentedToVirtual(object_water_effect_Matanimheader_000DE0));
@@ -648,7 +660,7 @@ void func_80A5A6B8(Actor* thisx, PlayState* play2) {
         Matrix_Pop();
     }
 
-    if ((this->unk_E34 > 1.0f) && (this->actor.params != ENWATEREFFECT_30C)) {
+    if ((this->unk_E34 > 1.0f) && (this->actor.params != ENWATEREFFECT_TYPE_GYORG_SHOCKWAVE)) {
         func_8012C2DC(play->state.gfxCtx);
         AnimatedMat_Draw(play, Lib_SegmentedToVirtual(object_water_effect_Matanimheader_000E40));
         Matrix_Scale(this->unk_DC8[3].y, this->unk_DC8[3].z, this->unk_DC8[3].y, MTXMODE_APPLY);
@@ -660,7 +672,8 @@ void func_80A5A6B8(Actor* thisx, PlayState* play2) {
 
     Matrix_Pop();
 
-    if ((this->actor.params == ENWATEREFFECT_309) || (this->actor.params == ENWATEREFFECT_30C)) {
+    if ((this->actor.params == ENWATEREFFECT_TYPE_GYORG_RIPPLES) ||
+        (this->actor.params == ENWATEREFFECT_TYPE_GYORG_SHOCKWAVE)) {
         func_8012C2DC(play->state.gfxCtx);
         AnimatedMat_Draw(play, Lib_SegmentedToVirtual(object_water_effect_Matanimheader_000E58));
         Matrix_Scale(this->unk_DC8[4].y, this->unk_DC8[4].z, this->unk_DC8[4].y, MTXMODE_APPLY);
@@ -670,7 +683,7 @@ void func_80A5A6B8(Actor* thisx, PlayState* play2) {
         gSPDisplayList(POLY_XLU_DISP++, object_water_effect_DL_000CD8);
     }
 
-    if (this->actor.params == ENWATEREFFECT_309) {
+    if (this->actor.params == ENWATEREFFECT_TYPE_GYORG_RIPPLES) {
         func_8012C2DC(play->state.gfxCtx);
 
         for (i = 0; i < ARRAY_COUNT(this->unk_144) / 2; i++, ptr++) {
diff --git a/src/overlays/actors/ovl_En_Water_Effect/z_en_water_effect.h b/src/overlays/actors/ovl_En_Water_Effect/z_en_water_effect.h
index 35aebd83e7..e4fb752dc2 100644
--- a/src/overlays/actors/ovl_En_Water_Effect/z_en_water_effect.h
+++ b/src/overlays/actors/ovl_En_Water_Effect/z_en_water_effect.h
@@ -18,13 +18,14 @@ typedef struct {
     /* 0x3C */ s16 unk_3C;
 } EnWaterEffectStruct; // size = 0x40
 
-enum {
-    /* 0x001 */ ENWATEREFFECT_1 = 1,
-    /* 0x309 */ ENWATEREFFECT_309 = 0x309,
-    /* 0x30A */ ENWATEREFFECT_30A,
-    /* 0x30B */ ENWATEREFFECT_30B,
-    /* 0x30C */ ENWATEREFFECT_30C,
-};
+typedef enum {
+    /* 0x001 */ ENWATEREFFECT_TYPE_FALLING_ROCK_SPAWNER = 1, // Spawner for falling flaming rocks,
+    /* 0x0FF */ ENWATEREFFECT_TYPE_FALLING_WATER_SPAWNER = 0xFF, // Spawner for water dripping from the ceiling
+    /* 0x309 */ ENWATEREFFECT_TYPE_GYORG_RIPPLES = 0x309, // Ripples on the surface when Gyrog enters/leaves the water
+    /* 0x30A */ ENWATEREFFECT_TYPE_GYORG_PRIMARY_SPRAY, // Large "funnel" of water that forms when Gyorg enters/leaves the water
+    /* 0x30B */ ENWATEREFFECT_TYPE_GYORG_SECONDARY_SPRAY, // Secondary "funnel" in the middle of the larger "funnel"
+    /* 0x30C */ ENWATEREFFECT_TYPE_GYORG_SHOCKWAVE, // Shockwave on the surface when Gyorg rams into the central platform
+} EnWaterEffectType;
 
 typedef struct EnWaterEffect {
     /* 0x000 */ Actor actor;
diff --git a/src/overlays/actors/ovl_Item_Inbox/z_item_inbox.c b/src/overlays/actors/ovl_Item_Inbox/z_item_inbox.c
index cdf0447e67..1f3fae3ac9 100644
--- a/src/overlays/actors/ovl_Item_Inbox/z_item_inbox.c
+++ b/src/overlays/actors/ovl_Item_Inbox/z_item_inbox.c
@@ -1,7 +1,7 @@
 /*
  * File: z_item_inbox.c
  * Overlay: ovl_Item_Inbox
- * Description:
+ * Description: Unused, can draw GetItem models. Perhaps intended to draw items inside chests.
  */
 
 #include "z_item_inbox.h"
diff --git a/src/overlays/actors/ovl_Obj_Dowsing/z_obj_dowsing.c b/src/overlays/actors/ovl_Obj_Dowsing/z_obj_dowsing.c
index cbbdf82ed0..0c0177d2f7 100644
--- a/src/overlays/actors/ovl_Obj_Dowsing/z_obj_dowsing.c
+++ b/src/overlays/actors/ovl_Obj_Dowsing/z_obj_dowsing.c
@@ -1,7 +1,7 @@
 /*
  * File: z_obj_dowsing.c
  * Overlay: ovl_Obj_Dowsing
- * Description:
+ * Description: Rumbles controller if switch or collectible/chest flag is unset
  */
 
 #include "z_obj_dowsing.h"