diff --git a/DESCRIPTION b/DESCRIPTION
index d4f2ff2..7d9309b 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -29,7 +29,6 @@ Imports:
     grDevices,
     igraph,
     lwgeom,
-    particles,
     patchwork,
     purrr,
     raster,
@@ -44,6 +43,7 @@ Suggests:
     elevatr,
   	MetBrewer,
   	metR,
+  	particles,
   	PrettyCols,
   	rayshader,
   	rcartocolor,
diff --git a/NEWS.md b/NEWS.md
index d8fd43f..de33463 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -2,7 +2,7 @@
 
 * Add `shatter()`
 * Fix missing namespace in `polygons()`
-* Move {rayshader}, {deldir}, {elevatr} from Imports to Suggests
+* Move {rayshader}, {deldir}, {elevatr}, {metR}, {particles} from Imports to Suggests
 * Add {PrettyCols} to Suggests
 * Lines in `lines()` are now centre aligned
 * Remove {magrittr} from Imports and use native pipe
diff --git a/R/flow_fields.R b/R/flow_fields.R
index 24c02e2..f505c64 100644
--- a/R/flow_fields.R
+++ b/R/flow_fields.R
@@ -22,48 +22,53 @@ flow_fields <- function(n = 10000,
                         line_col = c("#edf8fb", "#bfd3e6", "#9ebcda", "#8c96c6", "#8c6bb1", "#88419d", "#6e016b"),
                         bg_col = "lightgrey",
                         s = 1234) {
-  set.seed(s)
-  grid <- ambient::long_grid(seq(1, 10, length.out = granularity),
-                             seq(1, 10, length.out = granularity)) |>
-    dplyr::mutate(
-      x1 = .data$x + ambient::gen_simplex(x = .data$x, y = .data$y, frequency = x_freq),
-      y1 = .data$y + ambient::gen_simplex(x = .data$x, y = .data$y, frequency = y_freq)
-    )
+  # check if {particles} loaded
+  if (!requireNamespace("particles")) {
+    stop("Please install {particles} to use this function.")
+  } else {
+    set.seed(s)
+    grid <- ambient::long_grid(seq(1, 10, length.out = granularity),
+                               seq(1, 10, length.out = granularity)) |>
+      dplyr::mutate(
+        x1 = .data$x + ambient::gen_simplex(x = .data$x, y = .data$y, frequency = x_freq),
+        y1 = .data$y + ambient::gen_simplex(x = .data$x, y = .data$y, frequency = y_freq)
+      )
 
-  curl <- ambient::curl_noise(ambient::gen_perlin, x = grid$x1, y = grid$y1)
-  grid$angle <- atan2(curl$y, curl$x) - atan2(grid$y1, grid$x1)
+    curl <- ambient::curl_noise(ambient::gen_perlin, x = grid$x1, y = grid$y1)
+    grid$angle <- atan2(curl$y, curl$x) - atan2(grid$y1, grid$x1)
 
-  field <- as.matrix(grid, grid$x, value = grid$angle)
+    field <- as.matrix(grid, grid$x, value = grid$angle)
 
-  sim <- tidygraph::create_empty(n) |>
-    particles::simulate(alpha_decay = 0, setup = particles::aquarium_genesis(vel_max = 0)) |>
-    particles::wield(particles::reset_force, xvel = 0, yvel = 0) |>
-    particles::wield(particles::field_force, angle = field, vel = 0.1, xlim = c(-5, 5), ylim = c(-5, 5)) |>
-    particles::evolve(100, particles::record)
+    sim <- tidygraph::create_empty(n) |>
+      particles::simulate(alpha_decay = 0, setup = particles::aquarium_genesis(vel_max = 0)) |>
+      particles::wield(particles::reset_force, xvel = 0, yvel = 0) |>
+      particles::wield(particles::field_force, angle = field, vel = 0.1, xlim = c(-5, 5), ylim = c(-5, 5)) |>
+      particles::evolve(100, particles::record)
 
-  traces <- data.frame(do.call(rbind, lapply(sim$history, particles::position)))
-  names(traces) <- c("x", "y")
+    traces <- data.frame(do.call(rbind, lapply(sim$history, particles::position)))
+    names(traces) <- c("x", "y")
 
-  traces <-
-    traces |>
-    dplyr::mutate(particle = rep(1:n, 100)) |>
-    dplyr::group_by(.data$particle) |>
-    dplyr::mutate(colour = sample(line_col, 1, replace = TRUE))
+    traces <-
+      traces |>
+      dplyr::mutate(particle = rep(1:n, 100)) |>
+      dplyr::group_by(.data$particle) |>
+      dplyr::mutate(colour = sample(line_col, 1, replace = TRUE))
 
-  p <- ggplot2::ggplot() +
-    ggplot2::geom_path(data = traces,
-              mapping = ggplot2::aes(x = .data$x,
-                                     y = .data$y,
-                                     group = .data$particle,
-                                     colour = .data$colour),
-              size = 0.3,
-              alpha = alpha) +
-    ggplot2::coord_cartesian(expand = FALSE) +
-    ggplot2::scale_color_identity(guide = "none") +
-    ggplot2::theme_void() +
-    ggplot2::theme(panel.background = ggplot2::element_rect(fill = bg_col, colour = bg_col),
-                 plot.background = ggplot2::element_rect(fill = bg_col, colour = bg_col),
-                 legend.position = "none",
-                 plot.margin = ggplot2::unit(c(0, 0, 0, 0), "cm"))
-  p
+    p <- ggplot2::ggplot() +
+      ggplot2::geom_path(data = traces,
+                         mapping = ggplot2::aes(x = .data$x,
+                                                y = .data$y,
+                                                group = .data$particle,
+                                                colour = .data$colour),
+                         size = 0.3,
+                         alpha = alpha) +
+      ggplot2::coord_cartesian(expand = FALSE) +
+      ggplot2::scale_color_identity(guide = "none") +
+      ggplot2::theme_void() +
+      ggplot2::theme(panel.background = ggplot2::element_rect(fill = bg_col, colour = bg_col),
+                     plot.background = ggplot2::element_rect(fill = bg_col, colour = bg_col),
+                     legend.position = "none",
+                     plot.margin = ggplot2::unit(c(0, 0, 0, 0), "cm"))
+    return(p)
+  }
 }