I remem­ber it clearly—the day the inspi­ra­tion for Papa’s Mechan­i­cal Fish fell in my lap. I was sit­ting cross-legged on the base­ment floor of the Old Light­house Muse­um in Michi­gan City, Indi­ana, rum­mag­ing through a box of pho­tographs when a crum­bling, decades-old book­let slipped from a mani­la fold­er. The book­let told the tale of a local inven­tor named Lod­ner Phillips who in 1851 devel­oped a sub­ma­rine that not only had an air-puri­fy­ing sys­tem and a steam boil­er, but a chan­de­lier and vel­vet car­pets to boot. I was intrigued. But it wasn’t until I read this sen­tence that I became obsessed: “He so per­fect­ed his sub­ma­rine that one day he took his wife and chil­dren with him and spent a whole day explor­ing the bot­tom of the lake.”

Real­ly? A fam­i­ly ride under Lake Michi­gan in 1851? It was a Jules Verne nov­el… only true!

Con­vinced I’d just found the sub­ject for an amaz­ing non­fic­tion pic­ture book, I hur­ried up the stairs. What more did the muse­um have about Lod­ner Phillips? The cura­tor direct­ed me to a thin file con­tain­ing a clutch of fad­ed news­pa­per clip­pings; most pub­lished near­ly a cen­tu­ry ear­li­er. From them I gleaned the basics of Phillips’ life—his date of birth, a list of his accom­plish­ments, the year he died. But I didn’t uncov­er a sin­gle thing about him as hus­band, father, or under­wa­ter adven­tur­er. Not one thing. 

An online search was equal­ly fruit­less. Noth­ing exten­sive had been writ­ten about Phillips. His name did appear in a few mar­itime his­to­ries, but these pas­sages— mere men­tions really—added noth­ing to my under­stand­ing of him as a person.

Wrack­ing my brain, I jot­ted down any and all pos­si­ble sources of infor­ma­tion— coun­ty clerk records, estate rolls, tax records. The 1850 U.S. Cen­sus, I fig­ured, would be able to pro­vide the names and ages of Phillips’ chil­dren. And what about the Unit­ed States Patent Office? Sure­ly, the inven­tor sought a patent for his sub­ma­rine. I even includ­ed the Depart­ment of the Navy in hopes Phillips had writ­ten some­one there about his inven­tion. For good mea­sure, I con­tact­ed experts from the Chica­go His­to­ry Muse­um and the Great Lakes Mar­itime Museum.

And over the next few months, I mined some rich­es, includ­ing hand-drawn blue­prints of the submarine’s design, and archival pho­tographs of the ves­sel being sal­vaged from the Chica­go Riv­er. I even uncov­ered a detailed descrip­tion of the submarine’s work­ings writ­ten by the inven­tor him­self. But here’s the rub— not one of those sources pro­vid­ed clues to Phillips’ thoughts or feel­ings. There were no hints about his rela­tion­ship with his fam­i­ly, and not a sin­gle, con­crete detail about their incred­i­ble, under­wa­ter trip.

My idea for a non­fic­tion sto­ry was sunk (no pun intend­ed). Good his­to­ry, that is, his­to­ry that con­nects with young read­ers, requires a human view­point. My read­ers need­ed to be able to walk around in Phillips’ shoes, watch­ing the action unfold through his eyes.

I con­sid­ered aban­don­ing the project. But to do so felt as if I was turn­ing my back on Phillips. So I decid­ed to tell a dif­fer­ent story—part his and part mine—using those few, known frag­ments of his­to­ry, and fill­ing in the rest with my imag­i­na­tion. No, it wasn’t the book I set out to write. But in the end, it might be a bet­ter one. This tale is not just about a sub­ma­rine. It’s about per­se­ver­ance, the cre­ative impulse and the unwa­ver­ing faith of a lov­ing family.

I can’t doc­u­ment it, but I like to think Lod­ner Phillips pos­sessed all three.