@Jake 10 Glad to help if we can. Bonaire is such a great place to practice underwater navigation skills for so many reasons and helping your boys to hone their skills is excellent.
With the clarity of our waters, the typical (not always) lack of significant currents, the common terrain from site-to-site, and the ease of multiple exists (not all) should an error be made with easy correction and learning.
my wife and I use a combination of techniques. Our dive profiles here are generally very similar dive-to-dive. For us, we surface swim (snorkel) to the site surface marker (if it has one) or to the edge of the reef (light/dark blue line). This is typically ~20 of water and 75-100yds from shore. Generally calm, easy swims, sometimes a light current other times nothing to speak of. I have always taken a compass heading from the shore/truck to this point, or the other way around and I now take a heading back to the truck/exit point (My wife never does).
as we drop, we are looking at the terrain, we are looking for noticeable sponges, boulder coral formations, sand channels, etc. This is where my wife does very good, remembering a specific formation or two, growth, that stands out “for her” at the top of the reef and (this is important) the approximate depth of the formation.
now we begin our dive and start over the top soft corals to the typical 45° drop down. We head down assessing any current which is “generally” very light comparatively and decide to dive north or south (into the slight current). We gradually make our way to our MOD and move along (never a race), for us on 32% our MOD is usually 100-110. For much of the island the “first” reef bottoms out anywhere from about 75-100’, with a few exceptions.
once our computers put us at 5min NDL, we begin our ascent, usually still heading the same direction just gradually heading back up the reef unless one of us (me) has hit 1500psi. By the time someone (me) is at 1/2 tank, we turn around and continue working our angled ascent. This is when I am looking at the time of the dIve and the time we did our turn-around. I know when we droppen down and it started at the top of the reef, I know the current (if any) and have a basic idea how long our dive back to any navigational markers should be. We continuing coming up the reef and eventually over the top into the soft corals and one of two things happens…. She spots her navigational formation, or my mental timers says we are back.
now we use either my compass reciprocal heading or just basic direction and head into the shallows. We quickly hit 20ft but a safety “stop” is not needed as we just continue a slow gradual dive inward along the bottom gradually getting shallower. Remember that when shallow, on most sites, the sand ridges will run parallel to the shoreline, so you are diving perpendicular to them. Your gradual return is your safety/de-gas“ time. This is also when some great sights can be seen, octopus, eagle rays, and all kinds of juvenile reef fish in the shallower corals, also never ignoe rubble or sandy patches.
at about 6’ one of of will pop a head up and check our location with regards to the truck … from there any simple adjustments can me made and again never stop looking into the shallow blade corals because these can have some great finds.
sorry for any mistypes, feel free to ask any questions and we’d be glad to help. Again Bonaire is a great place to learn, practice, and improve underwater navigational skills.
enjoy ….