diff --git a/src/g_shared/a_fastprojectile.cpp b/src/g_shared/a_fastprojectile.cpp
index d45a9f2a8..c019fcbf6 100644
--- a/src/g_shared/a_fastprojectile.cpp
+++ b/src/g_shared/a_fastprojectile.cpp
@@ -28,6 +28,7 @@ void AFastProjectile::Tick ()
 	PrevX = x;
 	PrevY = y;
 	PrevZ = z;
+	fixed_t oldz = z;
 	PrevAngle = angle;
 
 	if (!(flags5 & MF5_NOTIMEFREEZE))
@@ -99,6 +100,8 @@ void AFastProjectile::Tick ()
 				}
 			}
 			z += zfrac;
+			UpdateWaterLevel (oldz);
+			oldz = z;
 			if (z <= floorz)
 			{ // Hit the floor
 
diff --git a/src/p_map.cpp b/src/p_map.cpp
index 9e927698b..b9e6dc125 100644
--- a/src/p_map.cpp
+++ b/src/p_map.cpp
@@ -64,7 +64,7 @@ CVAR (Int, sv_smartaim, 0, CVAR_ARCHIVE|CVAR_SERVERINFO)
 static void CheckForPushSpecial (line_t *line, int side, AActor *mobj);
 static void SpawnShootDecal (AActor *t1, const FTraceResults &trace);
 static void SpawnDeepSplash (AActor *t1, const FTraceResults &trace, AActor *puff,
-							 fixed_t vx, fixed_t vy, fixed_t vz, fixed_t shootz);
+							 fixed_t vx, fixed_t vy, fixed_t vz, fixed_t shootz, bool ffloor = false);
 
 static FRandom pr_tracebleed ("TraceBleed");
 static FRandom pr_checkthing ("CheckThing");
@@ -3555,7 +3555,7 @@ AActor *P_LineAttack (AActor *t1, angle_t angle, fixed_t distance,
 				*victim = trace.Actor;
 			}
 		}
-		if (trace.CrossedWater)
+		if (trace.Crossed3DWater || trace.CrossedWater)
 		{
 
 			if (puff == NULL)
@@ -3563,7 +3563,7 @@ AActor *P_LineAttack (AActor *t1, angle_t angle, fixed_t distance,
 				puff = P_SpawnPuff (t1, pufftype, hitx, hity, hitz, angle - ANG180, 2, flags|PF_HITTHING|PF_TEMPORARY);
 				killPuff = true;
 			}
-			SpawnDeepSplash (t1, trace, puff, vx, vy, vz, shootz);
+			SpawnDeepSplash (t1, trace, puff, vx, vy, vz, shootz, trace.Crossed3DWater != NULL);
 		}
 	}
 	if (killPuff && puff != NULL)
@@ -3925,11 +3925,11 @@ void P_RailAttack (AActor *source, int damage, int offset, int color1, int color
 			P_HitWater (thepuff, trace.Sector);
 		}
 	}
-	if (trace.CrossedWater)
+	if (trace.Crossed3DWater || trace.CrossedWater)
 	{
 		if (thepuff != NULL)
 		{
-			SpawnDeepSplash (source, trace, thepuff, vx, vy, vz, shootz);
+			SpawnDeepSplash (source, trace, thepuff, vx, vy, vz, shootz, trace.Crossed3DWater != NULL);
 		}
 	}
 	thepuff->Destroy ();
@@ -5469,13 +5469,16 @@ void SpawnShootDecal (AActor *t1, const FTraceResults &trace)
 //==========================================================================
 
 static void SpawnDeepSplash (AActor *t1, const FTraceResults &trace, AActor *puff,
-	fixed_t vx, fixed_t vy, fixed_t vz, fixed_t shootz)
+	fixed_t vx, fixed_t vy, fixed_t vz, fixed_t shootz, bool ffloor)
 {
-	if (!trace.CrossedWater->heightsec) return;
-	
-	fixed_t num, den, hitdist;
-	const secplane_t *plane = &trace.CrossedWater->heightsec->floorplane;
+	const secplane_t *plane; 
+	if (ffloor && trace.Crossed3DWater)
+		plane = trace.Crossed3DWater->top.plane;
+	else if (trace.CrossedWater && trace.CrossedWater->heightsec)
+		plane = &trace.CrossedWater->heightsec->floorplane;
+	else return;
 
+	fixed_t num, den, hitdist;
 	den = TMulScale16 (plane->a, vx, plane->b, vy, plane->c, vz);
 	if (den != 0)
 	{
diff --git a/src/p_mobj.cpp b/src/p_mobj.cpp
index 73a4cd49b..7eb2d39b9 100644
--- a/src/p_mobj.cpp
+++ b/src/p_mobj.cpp
@@ -4737,7 +4737,16 @@ bool P_HitWater (AActor * thing, sector_t * sec, fixed_t x, fixed_t y, fixed_t z
 	if (y == FIXED_MIN) y = thing->y;
 	if (z == FIXED_MIN) z = thing->z;
 	// don't splash above the object
-	if (checkabove && z > thing->z + (thing->height >> 1)) return false;
+	if (checkabove)
+	{
+		fixed_t compare_z = thing->z + (thing->height >> 1);
+		// Missiles are typically small and fast, so they might
+		// end up submerged by the move that calls P_HitWater.
+		if (thing->flags & MF_MISSILE)
+			compare_z -= thing->velz;
+		if (z > compare_z) 
+			return false;
+	}
 
 #if 0 // needs some rethinking before activation
 
diff --git a/src/p_trace.cpp b/src/p_trace.cpp
index bd00da36f..59dbe08f9 100644
--- a/src/p_trace.cpp
+++ b/src/p_trace.cpp
@@ -59,7 +59,9 @@ struct FTraceInfo
 	int sectorsel;		
 
 	bool TraceTraverse (int ptflags);
+	bool CheckPlane(const secplane_t &plane);
 	bool CheckSectorPlane (const sector_t *sector, bool checkFloor);
+	bool Check3DFloorPlane(const F3DFloor *ffloor, bool checkBottom);
 };
 
 static bool EditTraceResult (DWORD flags, FTraceResults &res);
@@ -90,17 +92,18 @@ bool Trace (fixed_t x, fixed_t y, fixed_t z, sector_t *sector,
 	inf.EnterDist = 0;
 	inf.TraceCallback = callback;
 	inf.TraceFlags = flags;
-	res.CrossedWater = NULL;
 	inf.Results = &res;
 	inf.inshootthrough = true;
-
-	res.HitType = TRACE_HitNone;
-
-	// Do a 3D floor check in the starting sector
-	memset(&res, 0, sizeof(res));
 	inf.sectorsel=0;
+	memset(&res, 0, sizeof(res));
+	/* // Redundant with the memset
+	res.HitType = TRACE_HitNone;
+	res.CrossedWater = NULL;
+	res.Crossed3DWater = NULL;
+	*/
 
 #ifdef _3DFLOORS
+	// Do a 3D floor check in the starting sector
 	TDeletingArray<F3DFloor*> &ff = sector->e->XFloor.ffloors;
 
 	if (ff.Size())
@@ -114,8 +117,16 @@ bool Trace (fixed_t x, fixed_t y, fixed_t z, sector_t *sector,
 		for(unsigned int i=0;i<ff.Size();i++)
 		{
 			F3DFloor * rover=ff[i];
+			if (!(rover->flags&FF_EXISTS))
+				continue;
 
-			if (!(rover->flags&FF_SHOOTTHROUGH) && rover->flags&FF_EXISTS)
+			if (rover->flags&FF_SWIMMABLE && res.Crossed3DWater == NULL)
+			{
+				if (inf.Check3DFloorPlane(rover, false))
+					res.Crossed3DWater = rover;
+			}
+
+			if (!(rover->flags&FF_SHOOTTHROUGH))
 			{
 				fixed_t ff_bottom=rover->bottom.plane->ZatPoint(x, y);
 				fixed_t ff_top=rover->top.plane->ZatPoint(x, y);
@@ -243,6 +254,26 @@ bool FTraceInfo::TraceTraverse (int ptflags)
 		fixed_t hitx, hity, hitz;
 		fixed_t dist;
 
+		// Deal with splashes in 3D floors
+#ifdef _3DFLOORS
+		if (CurSector->e->XFloor.ffloors.Size())
+		{
+			for(unsigned int i=0;i<CurSector->e->XFloor.ffloors.Size();i++)
+			{
+				F3DFloor * rover=CurSector->e->XFloor.ffloors[i];
+				if (!(rover->flags&FF_EXISTS))
+					continue;
+
+				// Deal with splashy stuff
+				if (rover->flags&FF_SWIMMABLE && Results->Crossed3DWater == NULL)
+				{
+					if (Check3DFloorPlane(rover, false))
+						Results->Crossed3DWater = rover;
+				}
+			}
+		}
+#endif
+
 		if (in->isaline)
 		{
 			int lineside;
@@ -287,7 +318,7 @@ bool FTraceInfo::TraceTraverse (int ptflags)
 				entersector = (lineside == 0) ? in->d.line->backsector : in->d.line->frontsector;
 				
 				// For backwards compatibility: Ignore lines with the same sector on both sides.
-				// This is the way Doom.exe did it and some WADs (e.g. Alien Vendetta MAP15 need it.
+				// This is the way Doom.exe did it and some WADs (e.g. Alien Vendetta MAP15) need it.
 				if (i_compatflags & COMPATF_TRACE && in->d.line->backsector == in->d.line->frontsector)
 				{
 					// We must check special activation here because the code below is never reached.
@@ -587,19 +618,8 @@ cont1:
 	return true;
 }
 
-bool FTraceInfo::CheckSectorPlane (const sector_t *sector, bool checkFloor)
+bool FTraceInfo::CheckPlane (const secplane_t &plane)
 {
-	secplane_t plane;
-
-	if (checkFloor)
-	{
-		plane = sector->floorplane;
-	}
-	else
-	{
-		plane = sector->ceilingplane;
-	}
-
 	fixed_t den = TMulScale16 (plane.a, Vx, plane.b, Vy, plane.c, Vz);
 
 	if (den != 0)
@@ -623,6 +643,38 @@ bool FTraceInfo::CheckSectorPlane (const sector_t *sector, bool checkFloor)
 	return false;
 }
 
+bool FTraceInfo::CheckSectorPlane (const sector_t *sector, bool checkFloor)
+{
+	secplane_t plane;
+
+	if (checkFloor)
+	{
+		plane = sector->floorplane;
+	}
+	else
+	{
+		plane = sector->ceilingplane;
+	}
+
+	return CheckPlane(plane);
+}
+
+bool FTraceInfo::Check3DFloorPlane (const F3DFloor *ffloor, bool checkBottom)
+{
+	secplane_t plane;
+
+	if (checkBottom)
+	{
+		plane = *(ffloor->bottom.plane);
+	}
+	else
+	{
+		plane = *(ffloor->top.plane);
+	}
+
+	return CheckPlane(plane);
+}
+
 static bool EditTraceResult (DWORD flags, FTraceResults &res)
 {
 	if (flags & TRACE_NoSky)
diff --git a/src/p_trace.h b/src/p_trace.h
index e13a7f905..8ce905da3 100644
--- a/src/p_trace.h
+++ b/src/p_trace.h
@@ -73,8 +73,9 @@ struct FTraceResults
 	BYTE Side;
 	BYTE Tier;
 	ETraceResult HitType;
-	sector_t *CrossedWater;
-	F3DFloor * ffloor;
+	sector_t *CrossedWater;		// For Boom-style, Transfer_Heights-based deep water
+	F3DFloor *Crossed3DWater;	// For 3D floor-based deep water
+	F3DFloor *ffloor;
 };
 
 enum